# 325 Maximum Size Subarray Sum Equals k

### Problem:

Given an array nums and a target value k, find the maximum length of a subarray that sums to k. If there isn't one, return 0 instead.

Note: The sum of the entire nums array is guaranteed to fit within the 32-bit signed integer range.

Example 1: Given nums = [1, -1, 5, -2, 3], k = 3, return 4. (because the subarray [1, -1, 5, -2] sums to 3 and is the longest)

Example 2: Given nums = [-2, -1, 2, 1], k = 1, return 2. (because the subarray [-1, 2] sums to 1 and is the longest)

Follow Up: Can you do it in O(n) time?

### Solutions:

``````public class Solution {
public int maxSubArrayLen(int[] nums, int k) {
int max = 0;
for (int i = 0; i < nums.length; i ++) {
int sum = 0;
for (int j = i; j < nums.length; j ++) {
sum += nums[j];
if (sum == k) {
max = Math.max(max, j - i + 1);
}
}
}
return max;
}
}
``````
``````public class Solution {
public int maxSubArrayLen(int[] nums, int k) {
int max = 0;
HashMap<Integer, Integer> sums = new HashMap<Integer, Integer>();
int sum = 0;
for (int i = 0; i < nums.length; i ++) {
sum += nums[i];
if (sum == k) {
max = Math.max(max, i + 1);
}
if (sums.containsKey(sum - k)) {
max = Math.max(max, i - sums.get(sum - k));
}
if (!sums.containsKey(sum)) {
sums.put(sum, i);
}
}
return max;
}
}
``````