Codeforces Round #450 (Div. 2)

Codeforces Round #450 (Div. 2)

http://codeforces.com/contest/900

A

 #include<bits/stdc++.h>
 using namespace std;
 #define lson l,mid,rt<<1
 #define rson mid+1,r,rt<<1|1
 #define sqr(x) ((x)*(x))
 #define pb push_back
 #define eb emplace_back
 #define maxn 100005
 #define eps 1e-8
 #define pi acos(-1.0)
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef pair<int,int> pii;
 typedef pair<long long,int>pli;
 typedef pair<int,char> pic;
 typedef pair<pair<int,string>,pii> ppp;
 typedef unsigned long long ull;
 const long long MOD=1e9+;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 int a[];
 int main(){
     #ifndef ONLINE_JUDGE
      //   freopen("1.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     int n;
     cin>>n;
     int u,v;
     for(int i=;i<n;i++){
         cin>>u>>v;
         if(u>) a[]++;
         else a[]++;
     }
     if(a[]<=||a[]<=) cout<<"YES"<<endl;
     else cout<<"NO"<<endl;
 }

B

模拟除法

 #include<bits/stdc++.h>
 using namespace std;
 #define lson l,mid,rt<<1
 #define rson mid+1,r,rt<<1|1
 #define sqr(x) ((x)*(x))
 #define pb push_back
 #define eb emplace_back
 #define maxn 100005
 #define eps 1e-8
 #define pi acos(-1.0)
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef pair<int,int> pii;
 typedef pair<long long,int>pli;
 typedef pair<int,char> pic;
 typedef pair<pair<int,string>,pii> ppp;
 typedef unsigned long long ull;
 const long long MOD=1e9+;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 int a[];
 ll fac[];
 int main(){
     #ifndef ONLINE_JUDGE
      //   freopen("1.txt","r",stdin);
     #endif
     int a,b,c;
     cin>>a>>b>>c;
     int co=;
     while(){
         a*=;
         int k=a/b;
         a%=b;
         if(k==c){
             cout<<co<<endl;
             return ;
         }
         co++;
         if(co>=) break;
     }
     cout<<-<<endl;

 }

C

找规律

 #include<bits/stdc++.h>
 using namespace std;
 #define lson l,mid,rt<<1
 #define rson mid+1,r,rt<<1|1
 #define sqr(x) ((x)*(x))
 #define pb push_back
 #define eb emplace_back
 #define maxn 100005
 #define eps 1e-8
 #define pi acos(-1.0)
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef pair<int,int> pii;
 typedef pair<long long,int>pli;
 typedef pair<int,char> pic;
 typedef pair<pair<int,string>,pii> ppp;
 typedef unsigned long long ull;
 const long long MOD=1e9+;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 int n;
 int a[maxn],cnt[maxn];

 int main(){
     #ifndef ONLINE_JUDGE
      //   freopen("1.txt","r",stdin);
     #endif
     cin>>n;
     int max1=,max2=;
     for(int i=;i<=n;i++) cin>>a[i];
     for(int i=;i<=n;i++){
         if(a[i]>max1){
             max2=max1;
             max1=a[i];
             cnt[a[i]]--;
         }
         else if(a[i]>max2){
             cnt[max1]++;
             max2=a[i];
         }
     }
     int max3=-maxn,ans;
     for(int i=;i<=n;i++){
         if(cnt[i]>max3){
             max3=cnt[i];
             ans=i;
         }
     }
     cout<<ans<<endl;

 }

D

记忆化搜索+容斥

 #include<bits/stdc++.h>
 using namespace std;
 #define lson l,mid,rt<<1
 #define rson mid+1,r,rt<<1|1
 #define sqr(x) ((x)*(x))
 #define pb push_back
 #define eb emplace_back
 #define maxn 100005
 #define eps 1e-8
 #define pi acos(-1.0)
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef pair<int,int> pii;
 typedef pair<long long,int>pli;
 typedef pair<int,char> pic;
 typedef pair<pair<int,string>,pii> ppp;
 typedef unsigned long long ull;
 const long long MOD=1e9+;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 int x,y;
 map<int,int>mp;

 ll pow_mul(ll a,ll b){
     ll ans=;
     while(b){
         if(b&) ans=(ans*a)%MOD;
         b>>=;
         a=(a*a)%MOD;
     }
     return ans;
 }

 ll dp(int x){
     if(x==) return ;
     if(mp.count(x)) return mp[x];
     mp[x]=pow_mul(,x-);
     for(int i=;i*i<=x;i++){
         if(x%i==){
             mp[x]=(mp[x]-dp(x/i)+MOD)%MOD;
             if(i!=x/i){
                 mp[x]=(mp[x]-dp(i)+MOD)%MOD;
             }
         }
     }
     return mp[x]=(mp[x]-dp()+MOD)%MOD;
 }

 int main(){
     #ifndef ONLINE_JUDGE
      //   freopen("1.txt","r",stdin);
     #endif
     cin>>x>>y;
     if(y%x){
         cout<<<<endl;
     }
     else{
         cout<<dp(y/x)<<endl;
     }

 }

E

DP

 #include<bits/stdc++.h>
 using namespace std;
 #define lson l,mid,rt<<1
 #define rson mid+1,r,rt<<1|1
 #define sqr(x) ((x)*(x))
 #define pb push_back
 #define eb emplace_back
 #define maxn 100005
 #define eps 1e-8
 #define pi acos(-1.0)
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef pair<int,int> pii;
 typedef pair<long long,int>pli;
 typedef pair<int,char> pic;
 typedef pair<pair<int,string>,pii> ppp;
 typedef unsigned long long ull;
 const long long MOD=1e9+;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */
 pii d[maxn];
 int f[][maxn], n, m, b[maxn];
 char a[maxn];

 int main(){
     #ifndef ONLINE_JUDGE
      //   freopen("1.txt","r",stdin);
     #endif
      cin >> n;
     for (int i = ; i <= n; i++)
         cin >> a[i];
     cin >> m;
     for (int i = ; i <= n; i++)
     {
         if (a[i] == '?')
             b[i] = b[i-] + ;
         else b[i] = b[i-];
         if (a[i] != 'a')
             f[][i] = f[][i-]+;
         if (a[i] != 'b')
             f[][i] = f[][i-]+;
         if (f[!(m&)][i] >= m)
             d[i] = {d[i-m].first + , -(b[i]-b[i-m]-d[i-m].second)};
         d[i] = max(d[i-], d[i]);
     }
     cout << - d[n].second;

 }