202407132009
tags: #sliding-window

var checkInclusion = function(s1, s2) {
	const map = new Map();
	for (const c of s1) {
		map.set(c, (map.get(c) ?? 0) + 1);
	}
	let start = 0;
	let count = 0;
	for (let end = 0; end < s2.length; end++) {
		map.set(s2[end], (map.get(s2[end]) ?? 0) - 1);
		if (map.get(s2[end]) >= 0) {
			count += 1;
		}
		if (end - start + 1 > s1.length) {
			map.set(s2[start], map.get(s2[start]) + 1);
			if (map.get(s2[start]) > 0) {
				count -= 1;
			}
			start += 1;
		}
		if (count === s1.length) {
			return true;
		}
	}
	return false;
};

Reference

https://leetcode.com/problems/permutation-in-string/