202410071438
tags: #prefix-sum

var subarraySum = function(nums, k) {
	const map = new Map();
	let sum = 0;
	let res = 0;
	map.set(0, 1);
	for (const num of nums) {
		sum += num;
		if (map.has(sum - k)) {
			res += map.get(sum - k);
		}
		map.set(sum, (map.get(sum) ?? 0) + 1);
	}
	return res;
};

Reference

https://leetcode.com/problems/subarray-sum-equals-k/