package subarraysumequalsk;

import java.util.HashMap;

import java.util.Map;

class Solution {

public static int subarraySum(int[] nums, int k) {

Map<Integer, Integer> minuses = new HashMap<>();

int total = 0;

if (nums[0] == k) {

total++;

}

minuses.put(nums[0], 1);

int newSum;

int prevSum = nums[0];

for (int i=1; i<nums.length; i++) {

newSum = prevSum + nums[i];

Integer number = minuses.get(newSum - k);

if (number != null) {

total += number;

}

if (newSum == k) {

total++;

}

minuses.merge(newSum, 1, Integer::sum);

prevSum = newSum;

}

return total;

}

public static void main(String[] args) {

int k = 2;

int[] arr = new int[]{1,1,1};

int i = subarraySum(arr, k);

System.out.print(i);

}

}