class Solution {
    public int findMaximumXOR(int[] nums) {
        Trie trie = new Trie();
        for (int num : nums) {
            trie.insert(num);
        }
        int max = Integer.MIN_VALUE;

        for (int num : nums) {
            TrieNode cur = trie.root;
            int curSum = 0;
            for (int i = 31; i >= 0; i--) {
                int curBit = (num >>>i) & 1;
                TrieNode next = cur.children[curBit ^ 1];
                if (next == null) {
                    cur = cur.children[curBit];
                } else {
                    curSum += (1 << i);
                    cur = next;
                }
            }
            max = Math.max(max, curSum);
        }
        return max;
    }
}
class TrieNode {
    TrieNode[] children = new TrieNode[2];
}
class Trie {
    TrieNode root = new TrieNode();
    public Trie() {}
    public void insert(int num) {
        TrieNode cur = root;
        for (int i = 31; i >= 0; i--) {
            int curBit = (num >>> i) & 1;
            TrieNode next = cur.children[curBit];
            if (next == null) {
                next = new TrieNode();
                cur.children[curBit] = next;
            }
            cur = next;
        }
    }
}