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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:
1 <= nums.length <= 2 * 104-1000 <= nums[i] <= 1000-107 <= k <= 107
Solution
using System.Collections.Generic;
public class Solution {
public int SubarraySum(int[] nums, int k) {
int tempSum = 0;
int ret = 0;
Dictionary<int, int> sumCount = new Dictionary<int, int>();
sumCount[0] = 1;
foreach (int i in nums) {
tempSum += i;
if (sumCount.ContainsKey(tempSum - k)) {
ret += sumCount[tempSum - k];
}
if (sumCount.ContainsKey(tempSum)) {
sumCount[tempSum] = sumCount[tempSum] + 1;
} else {
sumCount[tempSum] = 1;
}
}
return ret;
}
}