Software Engineering

# Get the Maximum XOR of Two Numbers in an Array in Java

## The challenge#

Given a non-empty array of numbers, a, a1, a2, … , an-1, where 0 ≤ ai < 231.

Find the maximum result of ai XOR aj, where 0 ≤ ij < n.

Could you do this in O(n) runtime?

Example:

```Input: [3, 10, 5, 25, 2, 8]
Output: 28
Explanation: The maximum result is 5 ^ 25 = 28.```

## The solution in Java#

We can very quickly resolve this challenge by performing a double loop and comparing our resultant:

``````class Solution {
public int findMaximumXOR(int[] nums) {
// store our maximum
int max = 0;

// loop through all numbers
for (int i=0; i<nums.length; i++) {
// loop through all our numbers again
for (int j=0; j<nums.length; j++) {
// keep a temp of the XOR
int tmp = nums[i] ^ nums[j];
// check if it's bigger
if (tmp>max) max = tmp;
}
}

// return our maximum
return max;
}
}
``````

While this solution does come to a correct answer, it is not in the `O(n)` of time due to our second loop, and our space complexity could be made better by not using an additional variable.