|
| 1 | +/** |
| 2 | + * @param {number[]} nums Array of numbers. |
| 3 | + * @param {number} k Goal sum of valid subarray. |
| 4 | + * @return {number} Count of subarrays for which elements sum up to k. |
| 5 | + * @summary Subarray Sum Equals K {@link https://leetcode.com/problems/subarray-sum-equals-k/} |
| 6 | + * @description Given array of integers and goal sum, return number of subarrays for which sum of elements equal k. |
| 7 | + * Space O(n) - Creating object literal (hashmap) with up to n keys. |
| 8 | + * Time O(n) - Input is traversed nums.length times. |
| 9 | + */ |
| 10 | +const subarraySum = (nums, k) => { |
| 11 | + let count = 0; |
| 12 | + let sum = 0; |
| 13 | + const results = { |
| 14 | + 0: 1, |
| 15 | + }; |
| 16 | + |
| 17 | + const length = nums.length; |
| 18 | + for (let i = 0; i < length; i++) { |
| 19 | + sum += nums[i]; |
| 20 | + if (results[sum - k]) count += results[sum - k]; |
| 21 | + results[sum] = results[sum] ? results[sum] + 1 : 1; |
| 22 | + } |
| 23 | + |
| 24 | + return count; |
| 25 | +}; |
0 commit comments