Codeforces Round #599

//

A Maximum Square : 

#include<bits/stdc++.h>
using namespace std;
const int N=1e5+10;
typedef long long ll;
int arr[N];
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        int n;
        scanf("%d",&n);
        for(int i=1;i<=n;i++) scanf("%d",&arr[i]);
        sort(arr+1,arr+1+n);
        int ans=0;
        for(int i=n;i>0;i--)
            ans=max(ans,min(arr[i],n-i+1));
        printf("%d\n",ans);
    }
    return 0;
}

B1 Character Swap (Easy Version)

#include <bits/stdc++.h>
#include <iostream>
#include <algorithm>
#include <cstdio>
#include <string>
#include <cstring>
#include <cstdlib>
#include <map>
#include <vector>
#include <set>
#include <queue>
#include <stack>
#include <cmath>
using namespace std;
#define mem(s,t) memset(s,t,sizeof(s))
#define pq priority_queue
#define pb push_back
#define fi first
#define se second
#define ac return 0;
#define ll long long
#define cin2(a,n,m)     for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) cin>>a[i][j];
#define rep_(n,m)  for(int i=1;i<=n;i++) for(int j=1;j<=m;j++)
#define rep(n) for(int i=1;i<=n;i++)
#define test(xxx) cout<<"  Test  " <<" "<<xxx<<endl;
#define TLE std::ios::sync_with_stdio(false);   cin.tie(NULL);   cout.tie(NULL);   cout.precision(10);
#define lc now<<1
#define rc now<<1|1
#define ls now<<1,l,mid
#define rs now<<1|1,mid+1,r
#define half no[now].l+((no[now].r-no[now].l)>>1)
#define ll long long
const int mxn = 1e6+5;
ll n,m,k,ans,cnt,col;
int a[mxn],b[27];
string str ,ch ;
int main()
{
    cin>>n;
    while(n--)
    {
        cin>>k;
        cin>>str>>ch;
        k = 0;
        memset(b,0,sizeof(b));
        for(int i=0;i<str.size() && k<3;i++)
        {
            b[str[i]-'a']++;
            if(str[i]!=ch[i])
            {
                a[++k]=i+1;
            }
        }
        if(k>=3 || k==1 )
            cout<<"No"<<endl;
        else if(k==2)
        {
            if(str[a[1]-1] == str[a[2]-1] && ch[a[2]-1] == ch[a[1]-1] )
                cout<<"Yes"<<endl;
            else
                cout<<"No"<<endl;
        }
    }
    return 0;
}

B2 Character Swap (Easy Version)  (来着聚聚）

#include <cstdio>
#include <iostream>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <cctype>
#include <string>
#include <queue>
#define mst(a,b) memset((a),(b),sizeof(a))
#define debug printf("debug\n")
#define INF 0x3f3f3f3f
#define lson lef,mid,rt<<1
#define rson mid+1,rig,rt<<1|1
const int maxn=1e5+5;
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
char str1[55],str2[55];
int cnt[30];
struct node{
    int lef,rig;
};
vector<node> ans;
int main()
{
    int t;scanf("%d",&t);
    while(t--){
        ans.clear();
        int n;scanf("%d",&n);
        scanf("%s",str1+1);
        scanf("%s",str2+1);
        bool flag=1;mst(cnt,0);
        for(int i=1;i<=n;i++){
            cnt[str1[i]-'a']++;
            cnt[str2[i]-'a']++;
        }
        for(int i=0;i<30;i++){
            if(cnt[i]&1){
                flag=0;break;
            }
        }
        if(!flag){
            puts("No");
        }else{
            puts("Yes");
            for(int i=1;i<=n;i++){
                if(str1[i]!=str2[i]){
                    for(int j=i+1;j<=n;j++){
                        if(str1[i]==str1[j]){
                            ans.push_back(node{j,i});
                            swap(str1[j],str2[i]);
                            break;
                        }
                        if(str1[i]==str2[j]){
                            ans.push_back(node{j,j});
                            swap(str1[j],str2[j]);
                            ans.push_back(node{j,i});
                            swap(str1[j],str2[i]);
                            break;
                        }
                    }
                }
            }
            int sz=ans.size();printf("%d\n",sz);
            for(int i=0;i<sz;i++){
                printf("%d %d\n",ans[i].lef,ans[i].rig);
            }
        }
    }
    return 0;
}

C Tile Painting

                      https://www.cnblogs.com/Shallow-dream/p/11823678.html

D 0-1 MST  

 　　　　　　https://www.cnblogs.com/Shallow-dream/p/11853785.html