A

太简单了，写完就删了

B
有很多人暴力搜，或者其他方法，样例不严谨过了，然后就被hack了

#include<bits/stdc++.h>
#define int long long
using namespace std;
signed main()
{int t;cin>>t;while (t--){string str,s,KK;cin>>str;cin>>s;int n = str.length();string HH[n];bool flag = false;for (int i=0;i<n;i++){HH[i]+= KK;KK+=str[i];reverse(KK.begin(),KK.end());HH[i]+= KK;reverse(KK.begin(),KK.end());if (HH[i].find(s)!=HH[i].npos) flag = true;}if (flag==true) cout<<"YES"<<endl;else cout<<"NO"<<endl;}
}

C
这道也很简单，思维题

#include <iostream>
#include <algorithm>
#include <set>
#include <cstring>
using namespace std;
#define int long long
signed main()
{int t;cin >> t;while (t--){char str[12];cin >> str + 1;// char aa[12],bb[12];int cou = 0;int a = 5, b = 5; //最高int A = 0, B = 0; //最低for (int i = 1; i <= 10; i++){++cou;if (i % 2 == 1){if (str[i] == '1')A++;else if (str[i] == '0')a--;else{A++;a--;}}else{if (str[i] == '1')B++;else if (str[i] == '0')b--;else{B++;b--;}}// cout << a << " " << A << endl;// cout << b << " " << B << endl;if (B > a || A > b)break;}cout << cou << endl;}
}

D
这道题也有很多人被hack了，不知道写的啥玩意
这道题想出来就很简单，想不出来就。。。。寄

#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> PII;
#define int long long
signed main()
{int t;cin >> t;while (t--){string str,s;cin>>str>>s;int i,j;for (i=str.length()-1,j = s.length()-1;i>=0;i--){if (str[i]==s[j]){--j;}else --i;if (j==-1) break;}if (j==-1) cout<<"YES"<<endl;else cout<<"NO"<<endl;}
}