Detect a Permuted Pattern in a Contiguous Window
Company: Meta
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Other
### Problem
Return whether s2 contains a contiguous substring that is a permutation of s1. Every character occurrence of s1 must be used once in that window.
```cpp
class Solution {
public:
bool checkInclusion(string s1, string s2);
};
```
### Examples
**Example 1:**
```text
s1 = "aab", s2 = "xabaq"
Output: true
Explanation: Window "aba" has two a characters and one b.
```
**Example 2:**
```text
s1 = "abc", s2 = "abxdce"
Output: false
Explanation: No length-three window has exactly a, b, c.
```
### Constraints
- Each string has 1..10000 characters drawn from English lowercase letters.
### Clarifying Questions
Compare multiplicities in fixed-length windows, including repeated letters.
```hint Read the boundary condition
What common summary identifies every permutation of a word?
```
### Contract considerations
Compare multiplicities in fixed-length windows, including repeated letters.
Overview: Detect a Permuted Pattern in a Contiguous Window. Return whether s2 contains a contiguous substring that is a permutation of s1.