LeetCode-in-All
560. Subarray Sum Equals K
Medium
Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k.
A subarray is a contiguous non-empty sequence of elements within an array.
Example 1:
Input: nums = [1,1,1], k = 2
Output: 2
Example 2:
Input: nums = [1,2,3], k = 3
Output: 2
Constraints:
1 <= nums.length <= 2 * 104-1000 <= nums[i] <= 1000-107 <= k <= 107
Solution
/**
* @param {number[]} nums
* @param {number} k
* @return {number}
*/
var subarraySum = function(nums, k) {
let tempSum = 0
let ret = 0
const sumCount = new Map()
sumCount.set(0, 1)
for (const num of nums) {
tempSum += num
if (sumCount.has(tempSum - k)) {
ret += sumCount.get(tempSum - k)
}
if (sumCount.has(tempSum)) {
sumCount.set(tempSum, sumCount.get(tempSum) + 1)
} else {
sumCount.set(tempSum, 1)
}
}
return ret
};
export { subarraySum }