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# Subarray Sum Equals K

## Description

Given an array of integers and an integer **k**, you need to find the total number of continuous subarrays whose sum equals to **k**.

**Example 1:**

> **Input:** nums = \[1,1,1], k = 2 
>
> **Output:** 2

**Note:**

1. The length of the array is in range \[1, 20,000].
2. The range of numbers in the array is \[-1000, 1000] and the range of the integer **k** is \[-1e7, 1e7].

## **Code**

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