8.3-8.7 usaco
summary:38
vijos1002:青蛙跳河。
dp+压缩。距离大于100可以直接%100.然后数据范围小了很多可以dp了。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- int f[100000];
- int a[105];
- bool vis[100000];
- int main(){
- int l,s,t,m;
- scanf("%d%d%d%d",&l,&s,&t,&m);
- rep(i,1,m) scanf("%d",&a[i]);
- sort(a+1,a+m+1);
- if(s==t){
- int ans=0;
- rep(i,1,m) if(!(a[i]%s)) ans++;
- printf("%d\n",ans);return 0;
- }
- int tmp,cnt=0;
- rep(i,1,m){
- if((tmp=a[i]-a[i-1])>100) vis[cnt+=100]=1;
- else vis[cnt+=tmp]=1;
- }
- rep(i,0,cnt+t) f[i]=100;f[0]=0;
- rep(i,0,cnt+t) rep(j,s,t) if(i>=j) f[i]=min(f[i],f[i-j]+vis[i]);
- int ans=105;
- rep(i,cnt,cnt+t) ans=min(ans,f[i]);
- printf("%d\n",ans);
- return 0;
- }
vijos1843:货车运输
最大生成树+lca。然而链剖太久没打WA了很久。id和idx容易混淆注意。是最大生成树森林处理一下,将边的权值弄到点的权值上。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- #define qwq(x) for(edge *o=head[x];o;o=o->next)
- #define lson x<<1,l,m
- #define rson x<<1|1,m+1,r
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=20005;
- const int maxn=100005;
- const int inf=0x7f7f7f7f;
- struct edge{
- int dist,from,to;edge *next;
- bool operator<(const edge &rhs)const{
- return dist>rhs.dist;}
- };
- edge e[maxn],edges[maxn<<1],*pt=edges,*head[nmax];
- int fa[nmax],n,m,pre[nmax],son[nmax],size[nmax],dep[nmax],tp[nmax],id[nmax],idx[nmax],w[nmax],sum[nmax<<2];
- void add(int u,int v,int d){
- pt->to=v;pt->dist=d;pt->next=head[u];head[u]=pt++;
- pt->to=u;pt->dist=d;pt->next=head[v];head[v]=pt++;
- }
- int find(int x){
- return fa[x]==x?x:fa[x]=find(fa[x]);
- }
- void dfs(int x){
- size[x]=1;
- qwq(x) if(o->to!=pre[x]){
- int to=o->to;pre[to]=x;dep[to]=dep[x]+1;w[to]=o->dist;
- dfs(to);size[x]+=size[to];
- if(!son[x]||size[to]>size[son[x]]) son[x]=to;
- }
- }
- void DFS(int x,int top){
- id[++id[0]]=x;idx[x]=id[0];tp[x]=top;
- if(son[x]) DFS(son[x],top);
- qwq(x) if(!idx[o->to]) DFS(o->to,o->to);
- }
- void build(int x,int l,int r){
- if(l==r) {
- sum[x]=w[id[l]];return ;
- }
- int m=(l+r)>>1;build(lson);build(rson);sum[x]=min(sum[x<<1],sum[x<<1|1]);
- }
- int query(int tl,int tr,int x,int l,int r){
- if(tl<=l&&tr>=r) return sum[x];
- int m=(l+r)>>1;int ans=inf;
- if(tl<=m) ans=min(ans,query(tl,tr,lson));
- if(tr>m) ans=min(ans,query(tl,tr,rson));
- return ans;
- }
- int qmax(int a,int b){
- if(find(a)!=find(b)) return -1;
- int ans=inf;
- while(tp[a]!=tp[b]){
- if(dep[tp[a]]>dep[tp[b]]) swap(a,b);
- ans=min(ans,query(idx[tp[b]],idx[b],1,1,n));
- b=pre[tp[b]];
- }
- if(dep[a]>dep[b]) swap(a,b);
- if(idx[a]==idx[b]) return ans;
- ans=min(ans,query(idx[a]+1,idx[b],1,1,n));
- return ans;
- }
- int main(){
- n=read(),m=read();
- rep(i,1,m) {
- edge &o=e[i];
- o.from=read(),o.to=read(),o.dist=read();
- }
- sort(e+1,e+m+1);
- rep(i,1,n) fa[i]=i;
- rep(i,1,m){
- edge &o=e[i];
- int ta=find(o.from),tb=find(o.to);
- if(ta!=tb){
- add(o.from,o.to,o.dist);
- fa[ta]=tb;
- }
- }
- clr(son,0);clr(idx,0);id[0]=0;
- rep(i,1,n) if(!pre[i]) dep[i]=0,dfs(i);
- rep(i,1,n) if(!idx[i]) DFS(i,i);
- build(1,1,n);
- int Q=read(),u,v;
- rep(i,1,Q){
- u=read(),v=read();
- printf("%d\n",qmax(u,v));
- }
- }
bzoj1650:
二分答案+贪心判断。和noip2015day2t1差不多。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=50005;
- int a[nmax],N,M,L;
- bool check(int x){
- int ans=0,pre=0;
- rep(i,1,N) {
- if(a[i]-a[pre]<x) ans++;
- else pre=i;
- }
- if(ans<=M) return true;
- return false;
- }
- int main(){
- L=read(),N=read(),M=read();
- rep(i,1,N) a[i]=read();
- sort(a+1,a+N+1);
- int l=0,r=L,mid,ans=0;
- while(l<=r){
- mid=(l+r)>>1;
- if(check(mid)) ans=mid,l=mid+1;
- else r=mid-1;
- }
- printf("%d\n",ans);
- return 0;
- }
bzoj1648:
边数点数少直接暴力dfs
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- #define qwq(x) for(edge *o=head[x];o;o=o->next)
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=1005;
- const int maxn=10005;
- const int inf=0x7f7f7f7f;
- struct edge{
- int to;edge *next;
- };
- edge edges[maxn],*pt=edges,*head[nmax];
- int a[nmax],ans[nmax];
- bool vis[nmax];
- void add(int u,int v){
- pt->to=v;pt->next=head[u];head[u]=pt++;
- }
- void dfs(int x){
- vis[x]=true;ans[x]++;
- qwq(x) if(!vis[o->to]) dfs(o->to);
- }
- int main(){
- int K=read(),N=read(),M=read(),u,v;
- rep(i,1,K) a[i]=read();
- rep(i,1,M) u=read(),v=read(),add(u,v);
- rep(i,1,K) clr(vis,false),dfs(a[i]);
- int res=0;
- rep(i,1,N) if(ans[i]==K) res++;
- printf("%d\n",res);
- return 0;
- }
bzoj1646:
简单bfs;
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define clr(x,c) memset(x,c,sizeof(x))
- const int nmax=200005;
- int q[nmax],dist[nmax];
- bool vis[nmax];
- int main(){
- int n,k;
- scanf("%d%d",&n,&k);
- int l=1,r=1;
- clr(vis,false);vis[n]=true;
- dist[n]=0;
- q[r]=n;
- while(l<=r){
- int x=q[l];l++;
- if(x==k){
- printf("%d\n",dist[x]);return 0;
- }
- if(x-1>=0&&!vis[x-1]) q[++r]=x-1,vis[x-1]=true,dist[x-1]=dist[x]+1;
- if(x+1<=200000&&!vis[x+1]) q[++r]=x+1,vis[x+1]=true,dist[x+1]=dist[x]+1;
- if(x+x<=200000&&!vis[x+x]) q[++r]=x+x,vis[x+x]=true,dist[x+x]=dist[x]+1;
- }
- return 0;
- }
bzoj1644:
bfs。不知道为什么我这样子写WA了。。。放一下代码求指点。。挖坑有空再写。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- #include<queue>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- char s[105];
- bool map[105][105];
- int f[105][105],from[105][105];
- queue<int>q,Q;
- int xx[5]={0,0,0,1,-1};
- int yy[5]={0,1,-1,0,0};
- int main(){
- int n,sa,sb,ta,tb;scanf("%d",&n);
- rep(i,1,n){
- scanf("%s",s+1);
- rep(j,1,n) {
- map[i][j]=s[j]=='x'?0:1;
- if(s[j]=='A') sa=i,sb=j;
- else if(s[j]=='B') ta=i,tb=j;
- }
- }
- clr(f,0x7f);
- f[sa][sb]=0;
- q.push(sa);Q.push(sb);
- int x,y,tx,ty;
- while(!q.empty()){
- x=q.front(),y=Q.front();q.pop();Q.pop();
- rep(i,1,4){
- tx=x+xx[i],ty=y+yy[i];
- if(tx<=0||ty<=0||tx>n||ty>n||!map[tx][ty]) continue;
- if(from[x][y]==i||x==sa&&y==sb) {
- if(f[x][y]<f[tx][ty])
- q.push(tx),Q.push(ty),f[tx][ty]=f[x][y],from[tx][ty]=i;
- }
- else if(f[x][y]<f[tx][ty]-1)
- q.push(tx),Q.push(ty),f[tx][ty]=f[x][y]+1,from[tx][ty]=i;
- }
- }
- printf("%d\n",f[ta][tb]);
- return 0;
- }
- /*
- 5
- ..Bx.
- .xxA.
- ...x.
- .x...
- ..x..*/
bzoj1643:
O(n^3)暴力,然后第四个数可以推出来。。因为写过一道搜索+剪枝有一个剪枝类似这样子所以会。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- #include<cmath>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- int a[105];
- int main(){
- int n,u,temp,orz,ans=0;
- scanf("%d",&n);
- int tmp=(int)sqrt(n)+1;
- rep(i,0,tmp) a[i]=i*i;
- rep(i,0,tmp) {
- rep(j,0,tmp) if(a[i]+a[j]<=n){
- rep(k,0,tmp) if((u=a[i]+a[j]+a[k])<=n){
- temp=n-u,orz=sqrt(temp);
- if(orz*orz==temp) ans++;
- }
- }
- }
- printf("%d\n",ans);
- return 0;
- }
bzoj1641:
floyed即可。。。然而一看到题目就二话不说二分答案+暴力dfs(总是觉得应该可以卡时过去。然而还是tle了。。、不过这种做法应该是对的吧
- /*#include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- #define qwq(x) for(edge *o=head[x];o;o=o->next)
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=305;
- const int maxn=25005;
- const int inf=0x7f7f7f7f;
- struct edge{
- int to,dist;edge *next;
- bool flag;
- };
- edge edges[maxn],*pt=edges,*head[nmax];
- int N,M,Q;
- bool vis[nmax];
- void add(int u,int v,int d){
- pt->to=v;pt->dist=d;pt->next=head[u];head[u]=pt++;
- }
- bool dfs(int x,int t){
- vis[x]=true;
- if(x==t) return true;
- qwq(x) if(!vis[o->to]&&o->flag){
- if(dfs(o->to,t)) return true;
- }
- return false;
- }
- bool check(int x,int s,int t){
- rep(i,1,N) qwq(i) if(o->dist<=x) o->flag=true;else o->flag=false;
- clr(vis,false);
- if(dfs(s,t)) return true;
- return false;
- }
- int main(){
- N=read(),M=read(),Q=read();
- int u,v,d,sum=0;
- rep(i,1,M) u=read(),v=read(),d=read(),add(u,v,d),sum=max(sum,d);
- rep(i,1,Q) {
- u=read(),v=read();
- int l=0,r=sum,ans=-1,mid;
- while(l<=r){
- mid=(l+r)>>1;
- if(check(mid,u,v)) ans=mid,r=mid-1;
- else l=mid+1;
- }
- printf("%d\n",ans);
- }
- }*/
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=305;
- const int maxn=25005;
- const int inf=0x7f7f7f7f;
- int dist[nmax][nmax];
- int main(){
- int N=read(),M=read(),Q=read(),u,v,d;
- clr(dist,0x7f);
- rep(i,1,M) u=read(),v=read(),d=read(),dist[u][v]=d;
- rep(k,1,N) rep(i,1,N) rep(j,1,N) if(dist[i][k]!=inf&&dist[k][j]!=inf)
- dist[i][j]=min(dist[i][j],max(dist[i][k],dist[k][j]));
- rep(i,1,Q) {
- u=read(),v=read();
- if(dist[u][v]==inf) printf("-1\n");
- else printf("%d\n",dist[u][v]);
- }
- return 0;
- }
bzoj1640:
直接模拟。。。然而没有看清题意WA了唉。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- const int nmax=2005;
- int a[nmax],ans[nmax];
- char c[5];
- int main(){
- int n;scanf("%d",&n);
- rep(i,1,n){
- scanf("%s",c);
- a[i]=c[0]-'A';
- }
- int l=1,r=n,tmp;
- rep(k,1,n){
- if(a[l]<a[r]) ans[k]=a[l],l++;
- else if(a[l]>a[r]) ans[k]=a[r],r--;
- else{
- for(int i=l,j=r;i<=j;i++,j--){
- if(a[i]<a[j]){
- tmp=l;break;
- }else if(a[i]>a[j]){
- tmp=r;break;
- }else if(i==j){
- tmp=l;break;
- }
- }
- ans[k]=a[tmp];
- tmp==l?l++:r--;
- }
- }
- rep(i,1,n){
- putchar('A'+ans[i]);
- if(i%80==0) putchar('\n');
- }
- return 0;
- }
- /*
- 10
- A
- C
- D
- E
- F
- B
- E
- D
- C
- B
- */
bzoj1639:
二分答案+贪心判断。这种模拟总有感觉自己会写WA,怀疑自己写错。但是只要用模拟一下数据的运算过程还是很容易判断写法的对错的。这也是模拟的调法吧。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=100005;
- const int inf=0x7f7f7f7f;
- int N,M,a[nmax];
- bool check(int x){
- int ans=0,cur=1,tmp;
- while(1){
- tmp=a[cur];
- if(tmp>x) return false;
- while(tmp<=x&&cur<=N) cur++,tmp+=a[cur];
- ans++;
- if(cur>N) break;
- }
- if(ans<=M) return true;
- return false;
- }
- int main(){
- N=read(),M=read();
- rep(i,1,N) a[i]=read();
- int l=0,r=inf,mid,ans=0;
- while(l<=r){
- mid=(l+r)>>1;
- if(check(mid)) ans=mid,r=mid-1;
- else l=mid+1;
- }
- printf("%d\n",ans);
- return 0;
- }
bzoj1638:
dfs。不会做,orz了hzwer(我原本的做法求方案数又是抱着应该可以卡过去的想法暴力dfs。。。stopstopstop小搜怡情爆搜伤身啊。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- #define qwq(x) for(edge *o=head[x];o;o=o->next)
- #define qaq(x) for(edge *o=h[x];o;o=o->next)
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=5005;
- const int maxn=50005;
- const int inf=0x7f7f7f7f;
- bool in[nmax];
- int s[maxn],t[maxn];
- int f[nmax],dp[nmax];
- struct edge{
- int to;edge *next;
- };
- edge edges[maxn],*pt=edges,*head[nmax];
- edge e[maxn],*p=e,*h[nmax];
- void add(int u,int v){
- pt->to=v;pt->next=head[u];head[u]=pt++;
- }
- void adde(int u,int v){
- p->to=v;p->next=h[u];h[u]=p++;
- }
- void dfs(int x){
- if(!head[x]) {
- dp[x]=1;return ;
- }
- qwq(x){
- if(!dp[o->to]) dfs(o->to);
- dp[x]+=dp[o->to];
- }
- }
- void DFS(int x){
- if(!h[x]) {
- f[x]=1;return ;
- }
- qaq(x){
- if(!f[o->to]) DFS(o->to);
- f[x]+=f[o->to];
- }
- }
- int main(){
- int N=read(),M=read(),u,v;
- rep(i,1,M) u=read(),v=read(),add(u,v),adde(v,u),in[v]=true,s[i]=u,t[i]=v;
- rep(i,1,N) if(!in[i]) dfs(i);
- DFS(N);
- int ans=0;
- rep(i,1,M) ans=max(ans,dp[t[i]]*f[s[i]]);
- printf("%d\n",ans);
- return 0;
- }
bzoj1637:
1就+1,0就-1,然后找乱搞就可以了。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=50005;
- struct node{
- int cur,x;
- bool operator<(const node&rhs)const{
- return cur<rhs.cur;}
- };
- node nodes[nmax];
- int sum[nmax],ll[nmax+nmax],rr[nmax+nmax];
- int main(){
- int n=read();
- rep(i,1,n) nodes[i].x=read(),nodes[i].cur=read();
- sort(nodes+1,nodes+n+1);
- rep(i,1,n) {
- node&o=nodes[i];
- if(o.x) sum[i]=sum[i-1]+1;
- else sum[i]=sum[i-1]-1;
- if(!ll[sum[i]+n]) ll[sum[i]+n]=i;
- else rr[sum[i]+n]=i;
- }
- int ans=0;
- rep(i,0,n+n){
- if(!rr[i]) continue;
- ans=max(ans,nodes[rr[i]].cur-nodes[ll[i]+1].cur);
- }
- printf("%d\n",ans);
- return 0;
- }
bzoj1636:
多次求区间最大最小差值。ST和线段树都可以搞。没写过ST写一下还是挺好写的。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- char s[100];
- void print(int x){
- int cur=0;
- if(!x) {
- putchar('0');putchar('\n');
- return;
- }
- while(x){
- s[++cur]=x%10+'0',x/=10;
- }
- dwn(i,cur,1) putchar(s[i]);
- putchar('\n');
- }
- const int nmax=50005;
- int a[nmax],f[nmax][20],g[nmax][20];
- int main(){
- int N=read(),Q=read(),u,v;
- rep(i,1,N) a[i]=read(),f[i][0]=g[i][0]=a[i];
- for(int k=1;(1<<k)<=N;k++)
- for(int i=1;i+(1<<k)-1<=N;i++)
- f[i][k]=max(f[i][k-1],f[i+(1<<k-1)][k-1]),g[i][k]=min(g[i][k-1],g[i+(1<<k-1)][k-1]);
- rep(i,1,Q){
- u=read(),v=read();
- int tmp;
- for(tmp=0;(1<<tmp)<=v-u+1;tmp++);tmp--;
- print(max(f[u][tmp],f[v-(1<<tmp)+1][tmp])-min(g[u][tmp],g[v-(1<<tmp)+1][tmp]));
- }
- return 0;
- }
bzoj1635:
差分序列!!!感觉好高大上的东西。就是可以区间内加减一个数。然后就可以啦。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=10005;
- int ans[nmax];
- struct node{
- int x,y;
- bool operator<(const node&rhs)const{
- return x<rhs.x||x==rhs.x&&y<rhs.y;}
- };
- node nodes[nmax];
- int main(){
- int N=read(),I=read(),H=read(),M=read(),u,v;
- rep(i,1,M) {
- node&o=nodes[i];
- o.x=read(),o.y=read();
- if(o.x>o.y) swap(o.x,o.y);
- }
- sort(nodes+1,nodes+M+1);
- rep(i,1,M){
- if(nodes[i].x==nodes[i-1].x&&nodes[i].y==nodes[i-1].y) continue;
- ans[nodes[i].x+1]--;ans[nodes[i].y]++;
- }
- rep(i,1,N) printf("%d\n",(ans[i]+=ans[i-1])+H);printf("\n");
- return 0;
- }
bzoj1634:
贪心。对于AB判断A前B后或者A后B前哪一种更优可以推出表达式。那么久可以确定顺序了。以点破面?。。。
- #include<cstdio>
- #include<cstring>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- #define ll long long
- const int nmax=100005;
- struct node{
- int w,t,num;
- bool operator<(const node&rhs)const{
- return rhs.w*t>w*rhs.t;}
- };
- node nodes[nmax];
- int main(){
- int N;scanf("%d",&N);
- rep(i,1,N) scanf("%d%d",&nodes[i].w,&nodes[i].t),nodes[i].num=i;
- sort(nodes+1,nodes+N+1);
- ll sum=0,ans=0;
- rep(i,1,N) ans+=sum*nodes[i].t<<1,sum+=nodes[i].w;
- printf("%lld\n",ans);
- return 0;
- }
bzoj1632:
bfs。多加一维来乱搞(然而我一直调不出来。。。挖坑。啊我为什么bfs总是WA啊。。。
bzoj1631:
两遍spfa就可以了。。。将边反过来存储就又变成单源最短路了。。以前见过。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<queue>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- #define qwq(x) for(edge *o=head[x];o;o=o->next)
- #define qaq(x) for(edge *o=h[x];o;o=o->next)
- int read(){
- int x=0;char c=getchar();int f=1;
- while(!isdigit(c)){
- if(c=='-') f=-1;c=getchar();
- }
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return f*x;
- }
- const int nmax=1005;
- const int maxn=100005;
- const int inf=0x7f7f7f7f;
- struct edge{
- int to,dist;edge*next;
- };
- edge edges[maxn],*pt=edges,*head[nmax];
- edge e[maxn],*p=e,*h[nmax];
- void add(int u,int v,int d){
- pt->to=v;pt->dist=d;pt->next=head[u];head[u]=pt++;
- }
- void adde(int u,int v,int d){
- p->to=v;p->dist=d;p->next=h[u];h[u]=p++;
- }
- queue<int>q;
- int dist[nmax],dis[nmax];
- bool inq[nmax];
- void spfa(int t){
- clr(inq,false);inq[t]=1;
- clr(dist,0x7f);dist[t]=0;
- q.push(t);
- while(!q.empty()){
- int x=q.front();q.pop();inq[x]=false;
- qwq(x) if(dist[o->to]>dist[x]+o->dist){
- dist[o->to]=dist[x]+o->dist;
- if(!inq[o->to]) q.push(o->to),inq[o->to]=true;
- }
- }
- }
- void SPFA(int t){
- clr(inq,false);inq[t]=1;
- clr(dis,0x7f);dis[t]=0;
- q.push(t);
- while(!q.empty()){
- int x=q.front();q.pop();inq[x]=false;
- qaq(x) if(dis[o->to]>dis[x]+o->dist){
- dis[o->to]=dis[x]+o->dist;
- if(!inq[o->to]) q.push(o->to),inq[o->to]=true;
- }
- }
- }
- int main(){
- int N=read(),M=read(),T=read(),u,v,d;
- rep(i,1,M){
- u=read(),v=read(),d=read();
- add(u,v,d);adde(v,u,d);
- }
- spfa(T);SPFA(T);
- int ans=-1;
- rep(i,1,N) ans=max(ans,dist[i]+dis[i]);
- printf("%d\n",ans);
- return 0;
- }
bzoj1630:
这可是道背包dp神题啊。挖坑似乎可以前缀和优化+滚动数组。。。然而我只会滚动数组。(防止mle。好劲啊这是。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=1e5+5;
- const int maxn=1e3+5;
- const int mod=1e6;
- int dp[nmax],cnt[maxn];
- int main(){
- int T=read(),A=read(),S=read(),B=read(),u;
- rep(i,1,A) u=read(),cnt[u]++;
- dp[0]=1;
- rep(i,1,T) dwn(j,B,1) rep(k,1,cnt[i]) {
- if(j<k) break;
- dp[j]=(dp[j]+dp[j-k])%mod;
- }
- int ans=0;
- rep(i,S,B) ans=(ans+dp[i])%mod;
- printf("%d\n",ans);
- return 0;
- }
bzoj1629:
贪心。。AB谁前谁后可以判断。和1634是同一种类型题。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=50005;
- const int inf=0x7f7f7f7f;
- struct node{
- int w,t;
- bool operator<(const node&rhs)const{
- return max(-t,w-rhs.t)<max(-rhs.t,rhs.w-t);}
- };
- node nodes[nmax];
- int main(){
- int n=read();
- rep(i,1,n) nodes[i].w=read(),nodes[i].t=read();
- sort(nodes+1,nodes+n+1);
- int ans=-inf,sum=0;
- rep(i,1,n) ans=max(ans,sum-nodes[i].t),sum+=nodes[i].w;
- printf("%d\n",ans);
- return 0;
- }
bzoj1628:
单调栈!边界没有处理好!!!注意边界。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=50005;
- int a[nmax],s[nmax];
- int main(){
- int N=read(),W=read(),u,v;
- rep(i,1,N) u=read(),a[i]=read();
- int r=0,ans=0;
- rep(i,1,N){
- while(r&&s[r]>a[i]) r--;
- if(s[r]!=a[i]) ans++;
- s[++r]=a[i];
- }
- printf("%d\n",ans);
- return 0;
- }
bzoj1627:
简单bfs。。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- #include<queue>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();int f=1;
- while(!isdigit(c)){
- if(c=='-') f=-1;c=getchar();
- }
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return f*x;
- }
- const int nmax=1005;
- const int orz=500;
- bool on[nmax][nmax],vis[nmax][nmax];
- int dist[nmax][nmax];
- struct node{
- int x,y;
- node(int x,int y):x(x),y(y){}
- };
- queue<node>q;
- int xx[5]={0,0,0,1,-1};
- int yy[5]={0,1,-1,0,0};
- int main(){
- int ta=read(),tb=read(),N=read(),u,v,d;
- ta+=orz,tb+=orz;
- clr(vis,false);clr(on,true);
- rep(i,1,N) u=read(),v=read(),on[u+orz][v+orz]=false;
- q.push(node(orz,orz));vis[orz][orz]=true;
- while(!q.empty()){
- node t=q.front();q.pop();
- rep(i,1,4){
- int tx=t.x+xx[i],ty=t.y+yy[i];
- if(tx&&ty&&tx<=1000&&ty<=1000&&!vis[tx][ty]&&on[tx][ty]) {
- vis[tx][ty]=true;dist[tx][ty]=dist[t.x][t.y]+1;
- q.push(node(tx,ty));
- if(tx==ta&&ty==tb){
- printf("%d\n",dist[tx][ty]);
- return 0;
- }
- }
- }
- }
- return 0;
- }
bzoj1626:
最小生成树。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- #include<cmath>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=1005;
- const int maxn=1000005;
- int fa[nmax],xi[nmax],yi[nmax];
- struct edge{
- int from,to;double dist;
- bool operator<(const edge&rhs)const{
- return dist<rhs.dist;}
- };
- edge edges[maxn];
- int find(int x){
- return fa[x]==x?x:fa[x]=find(fa[x]);
- }
- int main(){
- int N=read(),M=read(),u,v,ta,tb;
- rep(i,1,N) xi[i]=read(),yi[i]=read();
- rep(i,1,N) fa[i]=i;
- rep(i,1,M){
- u=read(),v=read();
- ta=find(u),tb=find(v);
- if(ta!=tb) fa[ta]=tb;
- }
- int cnt=0;
- rep(i,1,N-1) rep(j,i+1,N) {
- edge &o=edges[++cnt];
- o.from=i,o.to=j;
- o.dist=sqrt((double)(xi[i]-xi[j])*(xi[i]-xi[j])+(double)(yi[i]-yi[j])*(yi[i]-yi[j]));
- }
- sort(edges+1,edges+cnt+1);
- //rep(i,1,cnt) printf("%d %d %lf\n",edges[i].from,edges[i].to,edges[i].dist);
- double ans=0;int res=M;
- rep(i,1,cnt){
- ta=find(edges[i].from);tb=find(edges[i].to);
- if(ta!=tb) fa[ta]=tb,ans+=edges[i].dist,res++;
- if(res==N-1) break;
- }
- printf("%.2lf\n",ans);
- return 0;
- }
bzoj1625:
背包dp。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=3500;
- const int maxn=13000;
- int w[nmax],c[nmax];
- int dp[maxn];
- int main(){
- int N=read(),M=read();
- rep(i,1,N) w[i]=read(),c[i]=read();
- rep(i,1,N) dwn(j,M,w[i]) dp[j]=max(dp[j],dp[j-w[i]]+c[i]);
- printf("%d\n",dp[M]);
- return 0;
- }
bzoj1624:
floyed。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=105;
- const int maxn=10005;
- int dist[nmax][nmax];
- int ans[maxn];
- int main(){
- int N=read(),M=read();
- rep(i,1,M) ans[i]=read();
- rep(i,1,N) rep(j,1,N) dist[i][j]=read();
- rep(k,1,N) rep(i,1,N) rep(j,1,N)
- dist[i][j]=min(dist[i][j],dist[i][k]+dist[k][j]);
- int res=0;
- rep(i,1,M-1) res+=dist[ans[i]][ans[i+1]];
- printf("%d\n",res);
- return 0;
- }
bzoj1623:
贪心。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=50005;
- int a[nmax];
- int main(){
- int N=read(),M=read(),D=read(),L=read();
- rep(i,1,N) a[i]=read();
- sort(a+1,a+N+1);
- int ans=0;
- rep(i,1,N){
- if(a[i]-ans/M*D>=L) ans++;
- }
- printf("%d\n",ans);
- return 0;
- }
bzoj1622:
乱搞。。(这种模拟题我总是很虚啊。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- const int nmax=1005;
- const int maxn=105;
- char s[nmax][nmax],t[maxn][35];
- int ans[nmax];
- int lena[nmax],lenb[nmax];
- int main(){
- int N,M;
- scanf("%d%d",&N,&M);
- rep(i,1,N) {
- scanf("%s",s[i]);
- lena[i]=strlen(s[i]);
- rep(j,0,lena[i]-1)
- if(s[i][j]<'a') s[i][j]+=32;
- }
- rep(i,1,M) {
- scanf("%s",t[i]);
- lenb[i]=strlen(t[i]);
- rep(j,0,lenb[i]-1)
- if(t[i][j]<'a') t[i][j]+=32;
- }
- rep(i,1,N) rep(j,1,M) {
- int p=0,pt=0;
- while(p<lena[i]&&pt<lenb[j]){
- if(s[i][p]==t[j][pt]) pt++;
- p++;
- }
- if(pt==lenb[j]) ans[i]++;
- }
- rep(i,1,N) printf("%d\n",ans[i]);
- return 0;
- }
bzoj1621:
递归。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- int n,K;
- int dfs(int x){
- if((x+K)%2) return 1;
- if(x<=K) return 1;
- return dfs((x+K)/2)+dfs((x-K)/2);
- }
- int main(){
- n=read(),K=read();
- printf("%d\n",dfs(n));
- return 0;
- }
bzoj1620:
二分答案+贪心判断。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=100005;
- const int inf=0x7f7f7f7f;
- int N,M,a[nmax];
- bool check(int x){
- int ans=0,cur=1,tmp;
- while(1){
- tmp=a[cur];
- if(tmp>x) return false;
- while(tmp<=x&&cur<=N) cur++,tmp+=a[cur];
- ans++;
- if(cur>N) break;
- }
- if(ans<=M) return true;
- return false;
- }
- int main(){
- N=read(),M=read();
- rep(i,1,N) a[i]=read();
- int l=0,r=inf,mid,ans=0;
- while(l<=r){
- mid=(l+r)>>1;
- if(check(mid)) ans=mid,r=mid-1;
- else l=mid+1;
- }
- printf("%d\n",ans);
- return 0;
- }
bzoj1618:
背包dp。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=60005;
- const int maxn=105;
- const int inf=0x7f7f7f7f;
- int w[maxn],c[maxn];
- int f[nmax];
- int main(){
- int n=read(),h=read();
- rep(i,1,n) w[i]=read(),c[i]=read();
- clr(f,0x7f);f[0]=0;
- rep(i,1,n) rep(j,0,h) if(f[j]!=inf) f[j+w[i]]=min(f[j+w[i]],f[j]+c[i]);
- int ans=inf;
- rep(i,h,h+5005) ans=min(ans,f[i]);
- printf("%d\n",ans);
- return 0;
- }
bzoj1617:
区间dp。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int x;
- int read(){
- x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=2505;
- const int inf=0x7f7f7f7f;
- int cost[nmax],dp[nmax];
- int main(){
- int n=read(),m=read();
- rep(i,1,n) cost[i]=read(),cost[i]+=cost[i-1];
- clr(dp,0x7f);dp[0]=0;
- rep(i,1,n) rep(j,0,i-1) dp[i]=min(dp[i],dp[j]+cost[i-j]+m+m);
- printf("%d\n",dp[n]-m);
- return 0;
- }
bzoj1616:
多加一维然后dp转移即可。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=105;
- const int maxn=20;
- int dp[maxn][nmax][nmax],a[nmax][nmax];
- char s[nmax];
- int xx[5]={0,0,0,1,-1};
- int yy[5]={0,1,-1,0,0};
- int main(){
- int n=read(),m=read(),T=read();
- rep(i,1,n){
- scanf("%s",s);
- rep(j,1,m) a[i][j]=s[j-1]=='.'?1:0;
- }
- int sa=read(),ta=read(),sb=read(),tb=read();
- dp[0][sa][ta]=1;
- rep(i,1,T) rep(j,1,n) rep(k,1,m) {
- if(a[j][k]) {
- rep(o,1,4){
- int tx=j+xx[o],ty=k+yy[o];
- if(tx&&ty&&tx<=n&&ty<=m&&a[tx][ty]) dp[i][j][k]+=dp[i-1][tx][ty];
- }
- }else dp[i][j][k]=0;
- }
- printf("%d\n",dp[T][sb][tb]);
- return 0;
- }
bzoj1615:
乱搞。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();int f=1;
- while(!isdigit(c)){
- if(c=='-') f=-1;c=getchar();
- }
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x*f;
- }
- const int nmax=205;
- int x[nmax],y[nmax];
- double ans[nmax];
- int main(){
- int n=read();
- rep(i,1,n) x[i]=read(),y[i]=read();
- int cnt=0;bool f=false;
- rep(i,1,n) rep(j,1,n) if(i!=j){
- if(x[i]==x[j]) f=true;
- else ans[++cnt]=(double)(y[i]-y[j])/(x[i]-x[j]);
- }
- sort(ans+1,ans+cnt+1);
- int res=0;
- if(cnt) res++;
- rep(i,2,cnt) if(ans[i]!=ans[i-1]) res++;
- if(f) res++;
- printf("%d\n",res);
- return 0;
- }
bzoj1612:
spfa求路径最小值。。。都是差不多的啦。
- #include<cstdio>
- #include<iostream>
- #include<cstring>
- #include<queue>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define qwq(x) for(edge *o=head[x];o;o=o->next)
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=1005;
- const int maxn=10005;
- const int inf=0x7f7f7f7f;
- struct edge{
- int to,dist;edge *next;
- };
- edge edges[maxn],*pt=edges,*head[nmax];
- void add(int u,int v,int d){
- pt->to=v;pt->dist=d;pt->next=head[u];head[u]=pt++;
- pt->to=u;pt->dist=d;pt->next=head[v];head[v]=pt++;
- }
- struct node{
- int x,k;
- node(int x,int k):x(x),k(k){}
- };
- queue<node>q;
- int dist[nmax][nmax];
- bool inq[nmax][nmax];
- void spfa(int K,int n){
- clr(dist,0x7f);dist[1][0]=0;
- clr(inq,false);inq[1][0]=true;
- q.push(node(1,0));
- while(!q.empty()){
- node oo=q.front();q.pop();inq[oo.x][oo.k]=false;
- qwq(oo.x){
- int to=o->to;
- if(dist[to][oo.k]>max(dist[oo.x][oo.k],o->dist)) {
- dist[to][oo.k]=max(dist[oo.x][oo.k],o->dist);
- if(!inq[to][oo.k]){
- q.push(node(to,oo.k));inq[to][oo.k]=true;
- }
- }
- if(oo.k>=K) continue;
- if(dist[to][oo.k+1]>dist[oo.x][oo.k]){
- dist[to][oo.k+1]=dist[oo.x][oo.k];
- if(!inq[to][oo.k+1]){
- q.push(node(to,oo.k+1));inq[to][oo.k+1]=true;
- }
- }
- }
- }
- if(dist[n][K]==inf) printf("-1\n");
- else printf("%d\n",dist[n][K]);
- return ;
- }
- int main(){
- int n=read(),m=read(),p=read(),u,v,d;
- rep(i,1,m) u=read(),v=read(),d=read(),add(u,v,d);
- spfa(p,n);
- return 0;
- }
bzoj1612:
暴力dfsQAQ。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define clr(x,c) memset(x,c,sizeof(x))
- #define qwq(x) for(edge *o=head[x];o;o=o->next)
- #define qaq(x) for(edge *o=h[x];o;o=o->next)
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=105;
- const int maxn=4505;
- const int inf=0x7f7f7f7f;
- struct edge{
- int to;edge *next;
- };
- edge edges[maxn],*pt=edges,*head[nmax];
- edge e[maxn],*p=e,*h[nmax];
- int ans[nmax];
- bool vis[nmax];
- void add(int u,int v){
- pt->to=v;pt->next=head[u];head[u]=pt++;
- p->to=u;p->next=h[v];h[v]=p++;
- }
- void dfs(int x){
- qwq(x) if(!vis[o->to]) ans[o->to]++,vis[o->to]=true,dfs(o->to);
- }
- void DFS(int x){
- qaq(x) if(!vis[o->to]) ans[o->to]++,vis[o->to]=true,DFS(o->to);
- }
- int main(){
- int n=read(),m=read(),u,v;
- rep(i,1,m) u=read(),v=read(),add(u,v);
- rep(i,1,n) {
- clr(vis,false);dfs(i);
- }
- rep(i,1,n){
- clr(vis,false);DFS(i);
- }
- int res=0;
- rep(i,1,n) if(ans[i]==n-1) res++;
- printf("%d\n",res);
- return 0;
- }
bzoj1611:
对于每个点,能转移到该点必定没有被炸,那么可以利用这一点性质在bfs时转移!。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- #include<queue>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=305;
- const int inf=0x7f7f7f7f;
- int map[nmax][nmax],dist[nmax][nmax];
- bool vis[nmax][nmax];
- struct node{
- int x,y;
- node(int x,int y):x(x),y(y){}
- };
- queue<node>q;
- int xx[5]={0,0,0,1,-1};
- int yy[5]={0,1,-1,0,0};
- int main(){
- int m=read(),u,v,d;
- clr(map,0x7f);
- rep(i,1,m) {
- u=read(),v=read(),d=read();map[u][v]=min(map[u][v],d);
- rep(k,1,4) if(u+xx[k]>=0&&v+yy[k]>=0) map[u+xx[k]][v+yy[k]]=min(d,map[u+xx[k]][v+yy[k]]);
- }
- if(map[0][0]==inf){
- printf("0\n");return 0;
- }
- q.push(node(0,0));
- clr(vis,false);vis[0][0]=true;dist[0][0]=0;
- while(!q.empty()){
- node o=q.front();q.pop();
- rep(i,1,4){
- int x=o.x,y=o.y,tx=x+xx[i],ty=y+yy[i];
- if(tx<0||ty<0||map[tx][ty]-1<=dist[x][y]||vis[tx][ty]) continue;
- if(map[tx][ty]==inf){
- printf("%d\n",dist[x][y]+1);return 0;
- }
- q.push(node(tx,ty));dist[tx][ty]=dist[x][y]+1;vis[tx][ty]=true;
- }
- }
- printf("-1\n");
- return 0;
- }
bzoj4395:
暴力+bfs。多次bfs就可以了。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- #include<queue>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=105;
- const int maxn=20005;
- const int inf=0x7f7f7f7f;
- struct edge{
- int to,too;edge *next;
- };
- edge edges[maxn],*pt=edges,*head[nmax][nmax];
- bool on[nmax][nmax],vis[nmax][nmax];
- void add(int x,int y,int d,int w){
- pt->to=d;pt->too=w;pt->next=head[x][y];head[x][y]=pt++;
- }
- struct node{
- int a,b;
- node(int a,int b):a(a),b(b){}
- };
- queue<node>q;
- int xx[5]={0,0,0,1,-1};
- int yy[5]={0,1,-1,0,0};
- int main(){
- int n=read(),m=read();
- rep(i,1,m){
- int u=read(),v=read(),d=read(),w=read();
- add(u,v,d,w);
- }
- int ans=1,last=1;on[1][1]=true;
- while(1){
- q.push(node(1,1));
- clr(vis,0);vis[1][1]=true;
- while(!q.empty()){
- node x=q.front();q.pop();
- for(edge *o=head[x.a][x.b];o;o=o->next){
- if(!on[o->to][o->too]) on[o->to][o->too]=true,ans++;
- }
- rep(i,1,4){
- int tx=x.a+xx[i],ty=x.b+yy[i];
- if(tx&&ty&&tx<=n&&ty<=n){
- if(on[tx][ty]&&!vis[tx][ty])
- vis[tx][ty]=true,q.push(node(tx,ty));
- }
- }
- }
- if(last==ans) break;
- last=ans;
- }
- printf("%d\n",ans);
- return 0;
- }
bzoj1318:
神题。。这种题都不知道怎么想出来的。。。orzhzwer后勉勉强强懂了。。。然而太神了这。。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- #define ll long long
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=1000015;
- const int inf=0x7f7f7f7f;
- int n,ans=-1,last[nmax],next[nmax],a[nmax];
- ll sum[nmax];
- bool vis[nmax];
- void solve(int x){
- int len=0,rmax=inf;
- rep(i,x+1,n) {
- if(a[i]==1) break;
- if(!vis[a[i]]) vis[a[i]]=true;
- else {
- rmax=i;break;
- }
- }
- dwn(i,x,1){
- if(a[i]==1&&i!=x) break;
- rmax=min(rmax,next[i]);
- len=max(len,a[i]);
- if(i+len-1<=n&&i+len-1<rmax&&sum[i+len-1]-sum[i-1]==(ll)len*(len+1)/2) ans=max(ans,len);
- }
- rep(i,x+1,n) {
- if(a[i]==1) break;
- vis[a[i]]=false;
- }
- }
- void work(){
- clr(last,0x7f);
- dwn(i,n,1) {
- next[i]=last[a[i]];
- last[a[i]]=i;
- }
- rep(i,1,n) if(a[i]==1) solve(i);
- }
- int main(){
- n=read();
- rep(i,1,n) a[i]=read(),sum[i]=sum[i-1]+a[i];
- work();
- reverse(a+1,a+n+1);
- clr(sum,0);
- rep(i,1,n) sum[i]=sum[i-1]+a[i];
- work();
- printf("%d\n",ans);
- return 0;
- }
bzoj1306:
搜索+剪枝!。我写了三个剪枝但是tle了。到网上一看然后再加一个剪枝就卡过去了。。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- int f[4]={3,1,0,0};
- int ans[9],a[9],res=0,n;
- void dfs(int x,int y){
- if(ans[x]>a[x]) return ;
- if(ans[x]+(n-y+1)*3<a[x]) return ;
- if(x==n) {
- res++;return ;
- }
- if(y==n){
- int tmp=a[x]-ans[x];
- if(tmp==2) return ;
- ans[y]+=f[tmp];
- dfs(x+1,x+2);
- ans[y]-=f[tmp];
- }else{
- ans[x]+=3;dfs(x,y+1);ans[x]-=3;
- ans[x]++,ans[y]++,dfs(x,y+1),ans[x]--,ans[y]--;
- ans[y]+=3;dfs(x,y+1),ans[y]-=3;
- }
- }
- int main(){
- n=read();
- rep(i,1,n) a[i]=read();
- dfs(1,2);
- printf("%d\n",res);
- return 0;
- }
bzoj1303:
大于的就+1,小于的就-1,求中位数子串有多少个。。然后乱搞就可以了。
- #include<cstdio>
- #include<cstring>
- #include<iostream>
- #include<algorithm>
- using namespace std;
- #define rep(i,s,t) for(int i=s;i<=t;i++)
- #define dwn(i,s,t) for(int i=s;i>=t;i--)
- #define clr(x,c) memset(x,c,sizeof(x))
- int read(){
- int x=0;char c=getchar();
- while(!isdigit(c)) c=getchar();
- while(isdigit(c)) x=x*10+c-'0',c=getchar();
- return x;
- }
- const int nmax=200005;
- const int inf=0x7f7f7f7f;
- int a[nmax],cnt[nmax],sum[nmax];//qi ou
- int main(){
- int n=read(),m=read(),cur,u;
- rep(i,1,n){
- a[i]=read();
- if(a[i]==m) cur=i;
- a[i]+=100000;
- }
- m+=100000;
- sum[100000]=1;a[0]=100000;
- rep(i,1,cur-1){
- if(a[i]>m) a[i]=a[i-1]+1;
- else a[i]=a[i-1]-1;
- if(i%2) cnt[a[i]]++;
- else sum[a[i]]++;
- }
- int ans=0;
- rep(i,cur,n){
- if(a[i]>m) a[i]=a[i-1]+1;
- else if(a[i]==m) a[i]=a[i-1];
- else a[i]=a[i-1]-1;
- if(i%2) ans+=sum[a[i]];
- else ans+=cnt[a[i]];
- }
- printf("%d\n",ans);
- return 0;
- }
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