Codeforces Round #642 (Div. 3)(A-D)

题目链接：http://codeforces.com/contest/1353

视频讲解链接：https://space.bilibili.com/588753764/favlist?fid=968724164&ftype=create

代码：

A

 1 //
 2 //  main.cpp
 3 //  CF
 4 //
 5 //  Created by 韩金宇 on 2020/5/15.
 6 //  Copyright © 2020 韩金宇. All rights reserved.
 7 //
 8 
 9 #include <stdio.h>
10 #include <string.h>
11 #include <iostream>
12 #include <algorithm>
13 #include <vector>
14 #include <queue>
15 #include <set>
16 #include <map>
17 #include <list>
18 #include <map>
19 #include <string>
20 #include <math.h>
21 #include <stdlib.h>
22 #include <time.h>
23 using namespace std;
24 typedef double db;
25 typedef long long ll;
26 int main()
27 {
28     #ifdef ONLINE_JUDGE
29     #else
30         freopen("in.txt","r",stdin);
31     #endif
32        int t;
33        scanf("%d",&t);
34        while(t--){
35            ll n,m;
36            scanf("%lld%lld",&n,&m);
37            if(n==1)
38                printf("0\n");
39            else if(n==2)
40                printf("%lld\n",m);
41            else
42                printf("%lld\n",m<<1);
43            
44        }
45      return 0;
46 }

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B

//
//  main.cpp
//  CF
//
//  Created by 韩金宇 on 2020/5/15.
//  Copyright © 2020 韩金宇. All rights reserved.
//

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <list>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <time.h>
using namespace std;
typedef double db;
typedef long long ll;
const int maxn=2e5+10;
int main()
{
    #ifdef ONLINE_JUDGE
    #else
        freopen("in.txt","r",stdin);
    #endif
    int T;
    scanf("%d",&T);
    while(T--){
        int n,k;
        scanf("%d%d",&n,&k);
        int a[50],b[50];
        for(int i=0;i<n;i++)
            scanf("%d",a+i);
        for(int i=0;i<n;i++)
            scanf("%d",b+i);
        sort(a,a+n);
        sort(b,b+n,greater<int>());
        int kk=0;
        for(int i=0;i<n;i++)
        {
            if(b[i]>a[i])
            {
                if(kk>=k)
                break;
                swap(a[i],b[i]);
                kk++;
                
            }
        }
        int sum=0;
        for(int i=0;i<n;i++)
            sum+=a[i];
        printf("%d\n",sum);
    }
     return 0;
}

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C

//
//  main.cpp
//  CF
//
//  Created by 韩金宇 on 2020/5/15.
//  Copyright © 2020 韩金宇. All rights reserved.
//

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <list>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <time.h>
using namespace std;
typedef double db;
typedef long long ll;
const int maxn=2e5+10;
int main()
{
    #ifdef ONLINE_JUDGE
    #else
        freopen("in.txt","r",stdin);
    #endif
    int t;
    scanf("%d",&t);
    while(t--){
        int n;
        scanf("%d",&n);
        ll sum=0,beg=8;
        for(int i=1;i<=(n/2);i++){
            sum+=(i*beg);
            beg+=8;
        }
        printf("%lld\n",sum);
    }
     return 0;
}

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D

//
//  main.cpp
//  CF
//
//  Created by 韩金宇 on 2020/5/15.
//  Copyright © 2020 韩金宇. All rights reserved.
//

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <list>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <time.h>
using namespace std;
typedef double db;
typedef long long ll;
const int maxn=2e5+10;
pair<int,int > p3,p4,p;
struct cmp{
    bool operator()(const pair<int, int> p1,const pair<int, int> p2){
        if(p1.second-p1.first==p2.second-p2.first)
            return p1.first>p2.first;
        return p1.second-p1.first<p2.second-p2.first;
    }
};
priority_queue<pair<int, int>,vector<pair<int, int>>,cmp> q;
int main()
{
        #ifdef ONLINE_JUDGE
        #else
            freopen("in.txt","r",stdin);
        #endif
    int t;
    scanf("%d",&t);
    while(t--){
        int n;
        scanf("%d",&n);
        q.push({1,n});
        int a[maxn];
        int ops=1;
        while(q.size()){
            int l=q.top().first;
            int r=q.top().second;
            int mid=(l+r)/2;
            q.pop();
            a[mid]=ops++;
            if(l<=mid-1) q.push({l,mid-1});
            if(r>=mid+1) q.push({mid+1,r});
        }
        for(int i=1;i<=n;i++){
            printf("%d ",a[i]);
        }
        printf("\n");
    }
    return 0;
}

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