You have devised a new encryption technique which encodes a message by inserting between its characters randomly generated strings in a clever way. Because of pending patent issues we will not discuss in detail how the strings are generated and inserted into the original message. To validate your method, however, it is necessary to write a program that checks if the message is really encoded in the final string.
Given two strings s and t, you have to decide whether s is a subsequence of t, i.e. if you can remove characters from t such that the concatenation of the remaining characters is s.
Input
The input contains several testcases. Each is specified by two strings s, t of alphanumeric ASCII characters separated by whitespace. Input is terminated by EOF.
Output
For each test case output, if s is a subsequence of t.
Sample Input
sequence subsequence
person compression
VERDI vivaVittorioEmanueleReDiItalia
caseDoesMatter CaseDoesMatter
Sample Output
Yes
No
Yes
No
解题思路：题目的大概意思是给出每次两个字符，判断第一个字符串中的字母是否在第二个字符串中出现，需要注意的是，字符可以是不连续的但是顺序不能打乱。用一个循环依次判断至末尾就可以了。
程序代码：
#include<stdio.h>
#include<string.h>
const int N=100010;
char a[N],b[N];
int main()
{
int i,j;
while(scanf("%s%s",&a,&b)!=EOF)
{
for(i=0,j=0;a[i]!=‘\0‘&&b[j]!=‘\0‘;j++)
if(a[i]==b[j]) i++;
if(a[i]==‘\0‘) printf("Yes\n");
else printf("No\n");
}
return 0;
}