Permutation in String

Medium

Sliding Window

Given two strings s1 and s2, return true if s2 contains a permutation of s1, or false otherwise.

In other words, return true if one of s1's permutations is the substring of s2.

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

•1 <= s1.length, s2.length <= 10^4
•s1 and s2 consist of lowercase English letters.

Show Hints (3)

Hint 1: Use a fixed-size sliding window of length s1.length.

Hint 2: Compare character frequencies in the window with s1.

Hint 3: Use an array of size 26 to count character frequencies efficiently.

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Test Results

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