README.md

421. Maximum XOR of Two Numbers in an Array

Given an integer array nums, return the maximum result of nums[i] XOR nums[j], where 0 <= i <= j < n.

Example 1:

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

Example 2:

Input: nums = [14,70,53,83,49,91,36,80,92,51,66,70]
Output: 127

Constraints:

• 1 <= nums.length <= 2 * 105
• 0 <= nums[i] <= 231 - 1

Solutions (Python)

1. Solution

class Solution:
    def findMaximumXOR(self, nums: List[int]) -> int:
        trie = [[], []]
        ret = 0

        for num in nums:
            curr = trie
            for i in range(30, -1, -1):
                j = (num >> i) & 1
                if curr[j] == []:
                    curr[j].append([])
                    curr[j].append([])
                curr = curr[j]

            curr = trie
            x = 0
            for i in range(30, -1, -1):
                j = (num >> i) & 1
                if curr[j ^ 1] != []:
                    j ^= 1
                curr = curr[j]
                x |= j << i

            ret = max(ret, x ^ num)

        return ret