2017-10-20 NOIP模拟赛

Lucky Transformation

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
int n,k,cnt;
char s[];
int main(){
    freopen("trans.in","r",stdin);freopen("trans.out","w",stdout);
    //freopen("Cola.txt","r",stdin);
    while(scanf("%d%d",&n,&k)!=EOF){
        scanf("%s",s);cnt=;
        int rest=;
        for(int i=;i<n;i++){
            if(s[i]==''&&s[i+]==''){
                if(i>&&(i+)%==&&s[i-]==''&&s[i+]==''){
                    rest=k-cnt;break;
                }
                else if((i+)%==&&s[i+]==''&&s[i+]==''){
                    rest=k-cnt;break;
                }
                else{
                    if((i+)%==)s[i]='';
                    else s[i+]='';
                    cnt++;
                    if(cnt==k)break;
                }
            }
        }
        rest%=;
        if(rest==||cnt==k){
            printf("%s\n",s);
        }
        else{
            for(int i=;i<n;i++){
                if(s[i]==''&&s[i+]==''){
                    if((i+)%==)s[i]='';
                    else s[i+]='';
                    break;
                }
            }
            printf("%s\n",s);
        }
    }
}

100分 规律

Snake vs Block

#include<iostream>
#include<cstdio>
#define maxn 210
using namespace std;
int n,m,map[maxn][],num,ans,head[maxn],edge[maxn*+][maxn*+];
struct node{
    int to,pre,v;
}e[maxn**];
int make_id(int i,int j){return (i-)*+j;}
void Insert(int from,int to,int v){
    e[++num].to=to;
    e[num].v=v;
    e[num].pre=head[from];
    head[from]=num;
    edge[from][to]=num;
}
void dfs(int x,int y,int sc,int len){
    if(x>n){
        ans=max(ans,sc);
        return;
    }
    int now=make_id(x,y);
    for(int i=head[now];i;i=e[i].pre){
        int to=e[i].to;
        if(e[i].v==)continue;
        int xx=(to-)/+,yy=to%;
        if(yy==)yy=;
        e[i].v=;
        if(map[xx][yy]>=){
            int p=map[xx][yy];
            map[xx][yy]=;
            dfs(xx,yy,sc,len+p);
            map[xx][yy]=p;
        }
        else {
            if(len+map[xx][yy]<){ans=max(ans,sc);}
            else {
                int p=map[xx][yy];
                map[xx][yy]=;
                dfs(xx,yy,sc-p,len+p);
                map[xx][yy]=p;
            }
        }
        e[i].v=;
    }
}
int main(){
    freopen("snakevsblock.in","r",stdin);freopen("snakevsblock.out","w",stdout);
    //freopen("Cola.txt","r",stdin);
    scanf("%d",&n);
    for(int i=;i<=n;i++)
        for(int j=;j<=;j++){
            int id=make_id(i,j);
            if(j!=)Insert(id,make_id(i,j-),);//向左
            if(j!=)Insert(id,make_id(i,j+),);//向右
            Insert(id,make_id(i+,j),);//向下
            scanf("%d",&map[i][j]);
        }
    scanf("%d",&m);
    int x,y;
    for(int i=;i<=m;i++){
        scanf("%d%d",&x,&y);
        int id1=make_id(x,y),id2=make_id(x,y+);
        e[edge[id1][id2]].v=;
        e[edge[id2][id1]].v=;
    }
    dfs(,,,);
    printf("%d",ans);
}

30分 建图+dfs

/*
把豆豆和砖块丢在一起dp
f[i][j][k]:到第i行,蛇的长度还剩下j,从k位置出第i行的最大得分
g[j][l][r]:蛇的长度剩下j,从当前行l到r区间内仍为死亡的最大得分
初始化:对于每个i，g[j][k][k]=f[i-1][j-a[i][k]][k]+max(-a[i][k],0) 为初始状态
方程g[j][l][r] = max(g[j-a[i][l]][l+1][r] + max(-a[i][j],0),g[j-a[i][r]][l][r-1]+max(-a[i][k],0));
最后f[i][j][k] = max{g[j][l][r](1≤l≤k ≤r ≤5)}
*/
#include<iostream>
#include<cstdio>
#include<cstring>

#define N 207
#define M 10005

using namespace std;
int a[N][],f[N][M][],g[M][][];
bool flag[N][];
int n,m,maxi,ans,val;

inline int read()
{
    int x=,f=;char c=getchar();
    while(c>''||c<''){if(c=='-')f=-;c=getchar();}
    while(c>=''&&c<=''){x=x*+c-'';c=getchar();}
    return x*f;
}

int main()
{
    freopen("snakevsblock.in","r",stdin);
    freopen("snakevsblock.out","w",stdout);
    n=read();int x,y;
    for(int i=;i<=n;i++) for(int j=;j<;j++)
      a[i][j]=read();
    m=read();
    for(int i=;i<=m;i++)
    {
        x=read();y=read();
        flag[x][y-]=;
    }
    memset(f,-0x7f7f7f,sizeof f);
    f[][][]=;maxi=n*;

    for(int i=;i<=n;i++)
    {
        memset(g,-0x7f7f7f,sizeof g);
        for(int j=;j<=maxi;j++)
          for(int k=;k<;k++)
            if(j-a[i][k]>= && j-a[i][k]<=maxi)
              f[i][j][k]=g[j][k][k]=f[i-][j-a[i][k]][k]+max(-a[i][k],);

        for(int l=;l<=;l++)
          for(int j=,k=j+l;k<;j++,k++)
            for(int v=;v<=maxi;v++)
            {
                if(!flag[i][j]  && (val=v-a[i][j])>= && val<=maxi) g[v][j][k] = g[val][j + ][k] + max(-a[i][j], );//g[v][j][k]=max(g[v][j][k],g[val][j+1][k]+max(-a[i][j],0));
                if(!flag[i][k-]&& (val=v-a[i][k])>= && val<=maxi) g[v][j][k]=max(g[v][j][k],g[val][j][k-]+max(-a[i][k],));
                for(int to=j;to<=k;to++) f[i][v][to]=max(f[i][v][to],g[v][j][k]);
            }
    }

    for(int i=;i<=n;i++)
      for(int j=;j<=maxi;j++)
        for(int k=;k<;k++)
          ans=max(f[i][j][k],ans);

    printf("%d\n",ans);
    return ;
}

100分 动态规划

Ping

、

#include<iostream>
#include<cstring>
#include<cstdio>
#define maxn 100010
using namespace std;
int n,m,k,num,head[maxn],fa[maxn],dep[maxn],h[maxn],cnt;
bool vis[maxn],v[maxn];
int c[][<<];
struct node{
    int to,pre;
}e[maxn*];
struct Node{
    int l,r;
}p[];
void Insert(int from,int to){
    e[++num].to=to;
    e[num].pre=head[from];
    head[from]=num;
}
int count(int x){
    int res=;
    while(x){
        if(x&)res++;
        x>>=;
    }
    return res;
}
void dfs(int now,int father){
    fa[now]=father;dep[now]=dep[father]+;
    for(int i=head[now];i;i=e[i].pre){
        int to=e[i].to;
        if(to==father)continue;
        dfs(to,now);
    }
}
int sta;
bool lca(int a,int b){
    if(vis[a]||vis[b])return ;
    if(dep[a]<dep[b])swap(a,b);
    while(dep[a]>dep[b]){
        a=fa[a];
        if(vis[a])return ;
    }
    while(a!=b){
        a=fa[a];b=fa[b];
        if(vis[a]||vis[b])return ;
    }
    return ;
}
bool ok(int s){
    memset(vis,,sizeof(vis));
    int pos=;
    while(s){
        pos++;
        if(s&)vis[h[pos]]=;
        s>>=;
    }
    for(int i=;i<=k;i++){
        int a=p[i].l,b=p[i].r;
        if(lca(a,b))continue;
        else return ;
    }
    return ;
}
bool check(int x){
    for(int i=;i<=c[x][];i++){
        int s=c[x][i];
        if(ok(s)){
            sta=s;
            return ;
        }
    }
    return ;
}
int main(){
    freopen("ping.in","r",stdin);freopen("ping.out","w",stdout);
    //freopen("Cola.txt","r",stdin);
    scanf("%d%d",&n,&m);
    for(int i=;i<=(<<n)-;i++){
        int nu=count(i);
        c[nu][++c[nu][]]=i;
    }
    int x,y;
    for(int i=;i<=m;i++){
        scanf("%d%d",&x,&y);
        Insert(x,y);Insert(y,x);
        if(!v[x])h[++cnt]=x,v[x]=;
        if(!v[y])h[++cnt]=y,v[y]=;
    }
    dfs(,);
    scanf("%d",&k);
    for(int i=;i<=k;i++)
        scanf("%d%d",&p[i].l,&p[i].r);
    int l=,r=cnt,ans=;
    while(l<=r){
        int mid=(l+r)>>;
        if(check(mid))ans=mid,r=mid-;
        else l=mid+;
    }
    printf("%d\n",ans);
    int pos=;
    while(sta){
        pos++;
        if(sta&)printf("%d ",h[pos]);
        sta>>=;
    }
    return ;
}

30分 二分答案

#include <bits/stdc++.h>
using namespace std;
int n, m, P, u, v, to[], nxt[], p[], deep[], q[][];
int son[], fa[], size[], top[], dfsx[], cnt, ans;
int lca[], Q[], lr[][];
int sta[];
bool flag[];
void dfs(int x)
{
    size[x] = ;
    for (int i = p[x]; i != -; i = nxt[i])
        if (to[i] != fa[x])
        {
            fa[to[i]] = x;
            deep[to[i]] = deep[x] + ;
            dfs(to[i]);
            if (son[x] == - || size[to[i]] > size[son[x]]) son[x] = to[i];
            size[x] += size[to[i]];
        }
}
void dfs1(int x)
{
    dfsx[x] = ++cnt;
    if (son[x] != -) top[son[x]] = top[x], dfs1(son[x]);
    for (int i = p[x]; i != -; i = nxt[i])
        if (to[i] != fa[x] && to[i] != son[x])
            top[to[i]] = to[i], dfs1(to[i]);
}
int findlca(int x, int y)
{
    while ()
    {
        if (top[x] == top[y]) return deep[x] > deep[y]? y : x;
        if (deep[top[x]] > deep[top[y]]) x = fa[top[x]];
        else y = fa[top[y]];
    }
}
bool query(int x, int l, int r, int ll, int rr)
{
    if (l == ll && r == rr) return flag[x];
    int mid = (l + r) >> , L = x << , R = L | ;
    if (rr <= mid) return query(L, l, mid, ll, rr);
    else if (ll > mid) return query(R, mid + , r, ll, rr);
    else return query(L, l, mid, ll, mid) | query(R, mid + , r, mid + , rr);
}
void modify(int x, int l, int r, int to)
{
    flag[x] = true;
    if (l == r) return;
    int mid = (l + r) >> , L = x << , R = L | ;
    if (to <= mid) modify(L, l, mid, to);
    else modify(R, mid + , r, to);
}
bool Query(int x, int y)
{
    while ()
    {
        if (top[x] == top[y])
        {
            if (deep[x] < deep[y]) return query(, , cnt, dfsx[x], dfsx[y]);
            else return query(, , cnt, dfsx[y], dfsx[x]);
        }
        if (deep[top[x]] > deep[top[y]])
            if (query(, , cnt, dfsx[top[x]], dfsx[x])) return true;
            else x = fa[top[x]];
        else
        {
            if (query(, , cnt, dfsx[top[y]], dfsx[y])) return true;
            else y = fa[top[y]];
        }
    }
}
void work(int x)
{
    for (int i = p[x]; i != -; i = nxt[i])
        if (to[i] != fa[x])
            work(to[i]);
    for (int i = lr[x][]; i <= lr[x][]; i++)
        if (!Query(q[Q[i]][], q[Q[i]][]))
        {
            modify(, , cnt, dfsx[x]);
            sta[++ans] = x;
            return;
        }
}
bool cmp(int x, int y) {return lca[x] < lca[y];}
int main()
{
    freopen("ping.in","r",stdin);
    freopen("ping.out","w",stdout);
    scanf("%d%d", &n, &m);
    for (int i = ; i <= n; i++) p[i] = son[i] = -, top[i] = size[i] = fa[i] = deep[i] = ;
    for (int i = ; i <= n * ; i++) flag[i] = false;
    for (int i = ; i <= m; i++)
    {
        scanf("%d%d", &u, &v);
        u--, v--;
        to[i *  - ] = v;
        nxt[i *  - ] = p[u];
        p[u] = i *  - ;
        to[i * ] = u;
        nxt[i * ] = p[v];
        p[v] = i * ;
    }
    deep[] = ;
    dfs();
    cnt = ;
    dfs1();
    scanf("%d", &P);
    for (int i = ; i <= P; i++)
    {
        scanf("%d%d", &u, &v);
        u--, v--;
        q[i][] = u, q[i][] = v;
        lca[i] = findlca(u, v);
        Q[i] = i;
    }
    sort(Q + , Q + P + , cmp);
    for (int i = ; i <= n; i++) lr[i][] = P + , lr[i][] = ;
    for (int i = ; i <= P; i++)
    {
        lr[lca[Q[i]]][] = min(lr[lca[Q[i]]][], i);
        lr[lca[Q[i]]][] = max(lr[lca[Q[i]]][], i);
    }
    ans = ;
    work();
    printf("%d\n", ans);
    for (int i = ; i <= ans; i++) printf("%d ", sta[i] + );
    return ;
}

100分