Subarray Sum Equals K

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:

class Solution {
    public int subarraySum(int[] nums, int k) {
        Map<Integer,Integer> map = new HashMap<>();
        int result=0, sum=0;
        
        map.put(0,1);
        for(int i=0;i<nums.length; i++)
        {
            sum+=nums[i];
            if(map.containsKey(sum-k))
                result+=map.get(sum-k);
            map.put(sum,map.getOrDefault(sum,0)+1);
        }
        return result;
    }
}