Maximum Size Subarray Sum Equals K

Maximum Size Subarray Sum Equals K hash table

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?

Maximum Size Subarray Sum Equals K Solution

``````public class MaximumSizeSubarraySumEqualsK {
public int maxSubArrayLen(int[] nums, int k) {
if(nums.length == 0) {
return 0;
}

HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();

int maxLength = 0;

int total = 0;

map.put(0, -1);

for(int i = 0; i < nums.length; i++) {
total += nums[i];
if(map.containsKey(total - k)) {
maxLength = Math.max(maxLength, i - map.get(total - k));
}

if(!map.containsKey(total)) {
map.put(total, i);
}
}

return maxLength;
}
}``````