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
class Solution {
fun subarraySum(nums: IntArray, k: Int): Int {
var tempSum = 0
var ret = 0
val sumCount: MutableMap<Int, Int?> = HashMap()
sumCount[0] = 1
for (i in nums) {
tempSum += i
if (sumCount.containsKey(tempSum - k)) {
ret += sumCount[tempSum - k]!!
}
if (sumCount[tempSum] != null) {
sumCount[tempSum] = sumCount[tempSum]!! + 1
} else {
sumCount[tempSum] = 1
}
}
return ret
}
}