Codeforces Beta Round #4 (Div. 2 Only)

Codeforces Beta Round #4 (Div. 2 Only)

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))
typedef long long ll;
/*#ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
#endif */
struct sair{
    ll a,b;
    int pos;
    bool operator<(const sair&bb)const{
        return (b-a)<(bb.b-bb.a);
    }
};

int main(){
    #ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
    #endif
    int n;
    cin>>n;
    if(n%2==0&&n!=2&&n!=0) cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
}

B

判断给定时间在不在最大值之和和最小值之和之间即可

#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))
typedef long long ll;
/*#ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
#endif */
struct sair{
    ll a,b;
    int pos;
    bool operator<(const sair&bb)const{
        return (b-a)<(bb.b-bb.a);
    }
};

int a[1005],b[1005];

int main(){
    #ifndef ONLINE_JUDGE
     //   freopen("1.txt","r",stdin);
    #endif
    int n,m;
    cin>>n>>m;
    int Min=0,Max=0;
    for(int i=0;i<n;i++){
        cin>>a[i]>>b[i];
        Min+=a[i];
        Max+=b[i];
    }
    if(Min<=m&&m<=Max){
        cout<<"YES"<<endl;
        vector<int>ans;
        for(int i=0;i<n;i++){
            ans.push_back(a[i]);
            m-=a[i];
        }
        for(int i=0;i<ans.size();i++){
            if(m==0) break;
            int tmp=b[i]-a[i];
            if(m>tmp) m-=tmp;
            else {tmp=m,m=0;}
            ans[i]+=tmp;
        }
        for(int i=0;i<ans.size();i++){
            cout<<ans[i]<<" ";
        }
        cout<<endl;
    }
    else{
        cout<<"NO"<<endl;
    }

}

C

直接上map即可

#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))
typedef long long ll;
/*#ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
#endif */
struct sair{
    ll a,b;
    int pos;
    bool operator<(const sair&bb)const{
        return (b-a)<(bb.b-bb.a);
    }
};

int a[1005],b[1005];

string Change(int x){
    string str="";
    while(x){
        str+=char(x%10+'0');
        x/=10;
    }
    for(int i=0;i<str.length()/2;i++){
        char tmp=str[i];
        str[i]=str[str.length()-1-i];
        str[str.length()-1-i]=tmp;
    }
    return str;
}

int main(){
    #ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
    #endif
    int n;
    map<string,int>mp;
    cin>>n;
    string str;
    for(int i=1;i<=n;i++){
        cin>>str;
        if(mp[str]==0){
            cout<<"OK"<<endl;
            mp[str]=1;
        }
        else{
            string tmp=Change(mp[str]);
            mp[str]++;
            str+=tmp;
            mp[str]=1;
            cout<<str<<endl;
        }
    }

}

D

找最长上升子序列，DP水题

因为是二维排序的关系，所以最后一个位置的值不一定是最大的，所以要遍历一遍数组找最大值

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

int n,w,h;
struct sair{
    int w,h,pos;
}a[5005];

bool cmp(sair aa,sair bb){
    if(aa.h==bb.h) return aa.w<bb.w;
    return aa.h<bb.h;
}

int dp[5005],Index[5005];

void dfs(int pos){
    if(!a[pos].pos) return;
    dfs(Index[pos]);
    cout<<a[pos].pos<<" ";
}

int main(){
    #ifndef ONLINE_JUDGE
      //  freopen("1.txt","r",stdin);
    #endif
    int tot;
    cin>>tot>>a[1].w>>a[1].h;
    int i;
    n=1;
    for(i=1;i<=tot;i++){
        cin>>w>>h;
        if(w>a[1].w&&h>a[1].h){
            a[++n].w=w;
            a[n].h=h;
            a[n].pos=i;
        }
    }
    sort(a+1,a+n+1,cmp);

    for(int i=2;i<=n;i++){
        for(int j=1;j<=i;j++){
            if(a[i].w>a[j].w&&a[i].h>a[j].h&&dp[i]<=dp[j]){
                dp[i]=dp[j]+1;
                Index[i]=j;
            }
        }
    }
    int Max=0;
    int pos=0;
    for(int i=1;i<=n;i++){
        if(Max<dp[i]){
            Max=dp[i];
            pos=i;
        }
    }
    cout<<dp[pos]<<endl;
    dfs(pos);
}

当然，因为第一个比所有的都小，所以也可以从后往前DP,相当于DP最长下降子序列，这样下标为1的位置的值是最大的

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

int n,w,h;
struct sair{
    int w,h,pos;
}a[5005];

bool cmp(sair aa,sair bb){
    if(aa.h==bb.h) return aa.w<bb.w;
    return aa.h<bb.h;
}

int dp[5005],Index[5005];

void dfs(int pos){
    if(!a[pos].pos) return;
    dfs(Index[pos]);
    cout<<a[pos].pos<<" ";
}

int main(){
    #ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
    #endif
    int tot;
    cin>>tot>>a[1].w>>a[1].h;
    int i;
    n=1;
    for(i=1;i<=tot;i++){
        cin>>w>>h;
        if(w>a[1].w&&h>a[1].h){
            a[++n].w=w;
            a[n].h=h;
            a[n].pos=i;
        }
    }
    sort(a+1,a+n+1,cmp);
    for(int i=n-1;i>=1;i--){
        for(int j=i+1;j<=n;j++){
            if(a[i].w<a[j].w&&a[i].h<a[j].h&&dp[i]<=dp[j]){
                dp[i]=dp[j]+1;
                Index[i]=j;
            }
        }
    }
    cout<<dp[1]<<endl;
    int pos=Index[1];
    while(pos){
        cout<<a[pos].pos<<" ";
        pos=Index[pos];
    }
}