# Is Subsequence

Given a string**s**and a string**t**, check if**s**is subsequence of**t**.

You may assume that there is only lower case English letters in both**s**and**t**.**t**is potentially a very long (length \~= 500,000) string, and **s** is a short string (<=100).

A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (ie,`"ace"`is a subsequence of`"abcde"`while`"aec"`is not).

**Example 1:**\
**s**=`"abc"`, **t**=`"ahbgdc"`

Return`true`.

**Example 2:**\
**s**=`"axc"`, **t**=`"ahbgdc"`

Return`false`.

**Follow up:**\
If there are lots of incoming S, say S1, S2, ... , Sk where k >= 1B, and you want to check one by one to see if T has its subsequence. In this scenario, how would you change your code?

## Note

同向双指针分别指向两个字符串

## Code

```java
class Solution {
    public boolean isSubsequence(String s, String t) {
        int i = 0, j = 0;
        if (s.length() > t.length()) {
            return false;
        }

        while (i < s.length() && j < t.length()) {
            if (s.charAt(i) == t.charAt(j)) {
                i++;
            }
            j++;
        }

        return i == s.length();
    }
}
```
