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
func subarraySum(nums []int, k int) int {
tempSum := 0
ret := 0
sumCount := make(map[int]int)
sumCount[0] = 1
for _, num := range nums {
tempSum += num
if count, ok := sumCount[tempSum-k]; ok {
ret += count
}
sumCount[tempSum]++
}
return ret
}