# Permutation in String

#### Created: May 23, 2020 by [lek-tin]

##### Last updated: May 23, 2020

Given two strings `s1`

and `s2`

, write a function to return true if `s2`

contains the permutation of `s1`

. In other words, one of the first string’s permutations is the **substring** of the second string.

### Example 1:

```
Input: s1 = "ab" s2 = "eidbaooo"
Output: True
Explanation: s2 contains one permutation of s1 ("ba").
```

### Example 2:

```
Input:s1= "ab" s2 = "eidboaoo"
Output: False
```

#### Constraints:

- The input strings only contain lower case letters.
- The length of both given strings is in range
`[1, 10,000]`

.

### Solution

Java