【Trie】The XOR Largest Pair

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 typedef long long ll;
 4 const int N = 1e5+10;
 5 const int M = 3e6+10;
 6 int son[M][2];
 7 int a[N],n,idx;
 8 void Insert(int x){
 9     int p = 0 ;
10     for(int i=31;~i;i--){
11         int t = x >> i & 1 ;
12         if( !son[p][t] )
13             son[p][t] = ++idx;
14         p = son[p][t] ;
15     }
16 }
17 int Query(int x){
18     int p = 0 ;
19     int res = 0 ;
20     for(int i=31;~i;i--){
21         int t = x >> i & 1 ;
22         if( son[p][t^1] ){
23             res += 1<<i ;
24             p = son[p][t^1] ;
25         }else{
26             p = son[p][t] ;
27         }
28     }
29     return res ;
30 }
31 int main()
32 {
33     scanf("%d",&n);
34     for(int i=1;i<=n;i++)
35         scanf("%d",&a[i]),Insert(a[i]);
36     int res = 0 ;
37     for(int i=1;i<=n;i++)
38         res = max( Query(a[i]) , res );
39     printf("%d\n",res);
40     return 0 ;
41 }