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[105];

int main(){
    #ifndef ONLINE_JUDGE
       // freopen("1.txt","r",stdin);
    #endif
    cin>>n>>m;
    int flag=0;
    map<int,int>mp;
    for(int i=0;i<n;i++) cin>>str[i];
    for(int i=1;i<n;i++){
        if(str[i][0]==str[i-1][0]) flag=1;
    }
    if(!flag){
        if(m==1){
            cout<<"YES"<<endl;
        }
        else{
            for(int k=0;k<n;k++){
                for(int i=1;i<m;i++){
                    if(str[k][i]!=str[k][i-1]) flag=1;
                }
            }
            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[25];

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=1;i<=m;i++){
        cin>>a[i].num>>a[i].val;
    }
    sort(a+1,a+m+1,cmp);
    ll ans=0;
    for(int i=1;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=0;
        }
        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==0) 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-'0')*10+(ch2-'0');
}

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=25,pref=61;
    int ans=0;
    int co=1;
    for(int i=1;i<=n;i++){
        getline(cin,str);
      //  cout<<str<<" "<<i<<endl;
        char flag=str[7];
        int shi=Change(str[1],str[2]);
        int fen=Change(str[4],str[5]);
        if(flag=='p') shi+=12;
        if(shi==12&&flag=='a') shi=0;
        if(shi==24&&flag=='p') shi=12;
       // cout<<pres<<" "<<pref<<" "<<shi<<" "<<fen<<endl;
        if(shi==pres&&fen==pref) co++;
        else {
            co=1;
        }
        if(co>10) {
            co=1;
            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[25][25];

double dp[1<<19];

int main(){
    #ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
    #endif
    std::ios::sync_with_stdio(false);
    cin>>n;
    for(int i=0;i<n;i++){
        for(int j=0;j<n;j++){
            cin>>a[i][j];
        }
    }
    dp[(1<<n)-1]=1;///所有鱼都存在的情况
    for(int i=(1<<n)-1;i;i--){
        int num=0;
        for(int j=0;j<n;j++){
            if(i&(1<<j)) num++;///判断存活鱼的个数
        }
        for(int j=0;j<n;j++){
            if(i&(1<<j)){///j存活
                for(int k=j+1;k<n;k++){
                    if(i&(1<<k)){///k存活
                        dp[i-(1<<k)]+=dp[i]*a[j][k]*1.0/(num*(num-1)/2);  ///j吃k
                        dp[i-(1<<j)]+=dp[i]*a[k][j]*1.0/(num*(num-1)/2); ///k吃j
                    }
                }
            }
        }
    }
    for(int i=0;i<n;i++){
        cout<<dp[1<<i]<<" ";
    }
    cout<<endl;
}