Harbour.Space Scholarship Contest 2021-2022 (open for everyone, rated, Div. 1 + Div. 2) 

D.Backspace

从后往前取

#include<math.h>
#include<cstdio>
#include <iostream>
#include<algorithm>
#include<string>
#include<map>
#include<set>
#include <queue>
#include<stack>
#include<string.h>
using namespace std;
typedef long long ll;
const int N=1e6+10;
const double INF=1000000009;
const int mod=998244353;
string a,b;
int main()
{
    int t;cin>>t;
    string a,b;
    while(t--)
    {
        cin>>a>>b;
        reverse(a.begin(),a.end());
        reverse(b.begin(),b.end());
        int len1=a.length(),len2=b.length();
        int j=0,f=0;
        for(int i=0;i<len2;i++)
        {
            while(j<len1&&a[j]!=b[i]) j+=2;
            if(j>=len1) {f=1;break;}
            else if(a[j]==b[i]) j++;
        }
        if(f==1) cout<<"NO"<<endl;
        else cout<<"YES"<<endl;
    }
}