# 560. Subarray Sum Equals K

### Problem:

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].

### Solutions:

``````public class Solution {
public int subarraySum(int[] nums, int k) {
int[] sums = new int[nums.length + 1];
int sum = 0;
for (int i = 0; i < nums.length; i ++) {
sum += nums[i];
sums[i + 1] = sum;
}
int count = 0;
for (int i = 0; i < nums.length; i ++) {
int pre = sums[i];
for (int j = i; j < nums.length; j ++) {
int tmp = sums[j + 1] - pre;
if (tmp == k) {
count ++;
}
}
}
return count;
}
}
``````
``````public class Solution {
public int subarraySum(int[] nums, int k) {
int res = 0, sum = 0;
HashMap<Integer, Integer> count = new HashMap<Integer, Integer>();
count.put(0, 1);
for (int i = 0; i < nums.length; i ++) {
sum += nums[i];
if (count.containsKey(sum - k)) {
res += count.get(sum - k);
}
int add = 1;
if (count.containsKey(sum)) {