int findMaximumXOR(vector<int>& nums) {
    int mask = 0;
    int test_max = 0;
    int max = 0;
    unordered_set<int> s;
    for(long long i = 30; i >= 0; --i){
        mask |= 1ll << i;

        printf("n"BYTE_TO_BINARY_PATTERN, BYTE_TO_BINARY(mask));

        for(int num : nums){
            s.insert(num & mask);
        }

        test_max = max | 1 << i;
        for(int s_val : s){
            if(s.find(s_val ^ test_max) != s.end()){
                max = test_max;
                break;
            }
        }
        s.clear();
    }
    return max;
}