LeetCode-in-All

560. Subarray Sum Equals K

Medium

Given an array of integers nums and an integer k, return the total number of continuous subarrays whose sum equals to k.

Example 1:

Input: nums = [1,1,1], k = 2

Output: 2

Example 2:

Input: nums = [1,2,3], k = 3

Output: 2

Constraints:

Solution

function subarraySum(nums: number[], k: number): number {
    let tempSum: number = 0
    let ret: number = 0
    const sumCount: Map<number, number> = 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 }