LeetCode-in-Cpp
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
#include <vector>
#include <unordered_map>
class Solution {
public:
int subarraySum(std::vector<int>& nums, int k) {
int tempSum = 0;
int ret = 0;
std::unordered_map<int, int> sumCount;
sumCount[0] = 1;
for (int num : nums) {
tempSum += num;
if (sumCount.find(tempSum - k) != sumCount.end()) {
ret += sumCount[tempSum - k];
}
if (sumCount.find(tempSum) != sumCount.end()) {
sumCount[tempSum]++;
} else {
sumCount[tempSum] = 1;
}
}
return ret;
}
};