Yes写成了YES。。。。AC代码
#include<iostream>
#include<string.h>
#include<string>
using namespace std;
int main()
{
	string s;
	string t;
	while(cin>>s>>t)
	{
		int i,j;
		int len_of_s=s.length();
		int len_of_t=t.length();
		for(i=0,j=0;i<len_of_s&&j<len_of_t;)
		{
			if(s[i]==t[j])
				i++;
			j++;
		}
		if(i==len_of_s)cout<<"Yes"<<endl;
		else           cout<<"No"<<endl;
	}
	return 0;
}