202410122105
tags: #hash-map

const toMap = (word) => {
	const map = new Map();
	for (const c of word) {
		map.set(c, (map.get(c) ?? 0) + 1);
	}
	return map;
}

const intersect = (map1, map2) => {
	const set = new Set([...map1.keys()].concat([...map2.keys()]));
	const newMap = new Map();
	for (const key of set) {
		const intersectCount = Math.min(map1.get(key) ?? 0, map2.get(key) ?? 0);
		if (intersectCount !== 0) {
			newMap.set(key, intersectCount);
		}
	}
	return newMap;
}

var commonChars = function(words) {
	let wordMap = toMap(words[0]);
	for (let i = 1; i < words.length; i++) {
		wordMap = intersect(wordMap, toMap(words[i]));
	}
	const res = [];
	for (const [key, val] of wordMap.entries()) {
		for (let i = 0; i < val; i++) {
			res.push(key);
		}
	}
	return res;
};

Reference

https://leetcode.com/problems/find-common-characters/