Codeforces Beta Round #16 (Div. 2 Only)

Codeforces Beta Round #16 (Div. 2 Only)

http://codeforces.com/contest/16

A

水题

 #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 maxn 500005
 typedef long long ll;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 int n,m;
 string str[];

 int main(){
     #ifndef ONLINE_JUDGE
        // freopen("1.txt","r",stdin);
     #endif
     cin>>n>>m;
     int flag=;
     map<int,int>mp;
     for(int i=;i<n;i++) cin>>str[i];
     for(int i=;i<n;i++){
         if(str[i][]==str[i-][]) flag=;
     }
     if(!flag){
         if(m==){
             cout<<"YES"<<endl;
         }
         else{
             for(int k=;k<n;k++){
                 for(int i=;i<m;i++){
                     if(str[k][i]!=str[k][i-]) flag=;
                 }
             }
             if(flag) cout<<"NO"<<endl;
             else  cout<<"YES"<<endl;
         }
     }
     else{
         cout<<"NO"<<endl;
     }
 }

B

贪心

 #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 maxn 500005
 typedef long long ll;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 struct sair{
     ll num,val;
 }a[];

 bool cmp(sair a,sair b){
     return a.val>b.val;
 }

 int main(){
     #ifndef ONLINE_JUDGE
        // freopen("1.txt","r",stdin);
     #endif
     ll n,m;
     cin>>n>>m;
     for(int i=;i<=m;i++){
         cin>>a[i].num>>a[i].val;
     }
     sort(a+,a+m+,cmp);
     ll ans=;
     for(int i=;i<=m;i++){
         if(n>=a[i].num){
             ans+=a[i].num*a[i].val;
             n-=a[i].num;
         }
         else if(n<a[i].num){
             ans+=a[i].val*n;
             n=;
         }
         if(!n) break;
     }
     cout<<ans<<endl;
 }

C

gcd

 #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 maxn 500005
 typedef long long ll;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 ll gcd(ll a,ll b){
     if(b==) return a;
     return gcd(b,a%b);
 }
 int main(){
     #ifndef ONLINE_JUDGE
        // freopen("1.txt","r",stdin);
     #endif
     ll a,b,c,d;
     cin>>a>>b>>c>>d;
     ll x=gcd(c,d);
     c/=x;
     d/=x;
     x=min(a/c,b/d);
     cout<<c*x<<" "<<d*x<<endl;
 }

D

模拟

 #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 maxn 500005
 typedef long long ll;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */
 string str;

 int Change(char ch1,char ch2){
     return (ch1-'')*+(ch2-'');
 }

 int main(){
     #ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
     #endif
    // std::ios::sync_with_stdio(false);
     int n;
     scanf("%d%*c",&n);
     int pres=,pref=;
     int ans=;
     int co=;
     for(int i=;i<=n;i++){
         getline(cin,str);
       //  cout<<str<<" "<<i<<endl;
         char flag=str[];
         int shi=Change(str[],str[]);
         int fen=Change(str[],str[]);
         if(flag=='p') shi+=;
         if(shi==&&flag=='a') shi=;
         if(shi==&&flag=='p') shi=;
        // cout<<pres<<" "<<pref<<" "<<shi<<" "<<fen<<endl;
         if(shi==pres&&fen==pref) co++;
         else {
             co=;
         }
         if(co>) {
             co=;
             ans++;
         }
         if(shi<pres||(shi==pres&&fen<pref)){
             ans++;
         }
         pres=shi;
         pref=fen;
     }
     cout<<ans<<endl;
 }

E

状压DP

dp(i吃掉j)=dp(i和j同时存在)∗p(i战胜j)的概率∗prob(i和j相遇)的概率

 #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 maxn 500005
 typedef long long ll;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 int n;
 double a[][];

 double dp[<<];

 int main(){
     #ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     cin>>n;
     for(int i=;i<n;i++){
         for(int j=;j<n;j++){
             cin>>a[i][j];
         }
     }
     dp[(<<n)-]=;///所有鱼都存在的情况
     for(int i=(<<n)-;i;i--){
         int num=;
         for(int j=;j<n;j++){
             if(i&(<<j)) num++;///判断存活鱼的个数
         }
         for(int j=;j<n;j++){
             if(i&(<<j)){///j存活
                 for(int k=j+;k<n;k++){
                     if(i&(<<k)){///k存活
                         dp[i-(<<k)]+=dp[i]*a[j][k]*1.0/(num*(num-)/);  ///j吃k
                         dp[i-(<<j)]+=dp[i]*a[k][j]*1.0/(num*(num-)/); ///k吃j
                     }
                 }
             }
         }
     }
     for(int i=;i<n;i++){
         cout<<dp[<<i]<<" ";
     }
     cout<<endl;
 }