2023-8-25 最大异或对

题目链接：最大异或对

#include 
#include 

using namespace std;

const int N = 100010, M = 31 * N;

int a[N];
int son[M][2], idx;

void insert(int x)
{
    int p = 0;
    for(int i = 30; i >= 0; i --)
    {
        int u = x >> i & 1;
        if(!son[p][u]) son[p][u] = ++ idx;
        p = son[p][u];
    }
}

int query(int x)
{
    int p = 0, res = 0;
    for(int i = 30; i >= 0; i --)
    {
        int u = x >> i & 1;
        if(son[p][!u])
        {
            p = son[p][!u];
            res = res * 2 + !u;
        }
        else
        {
            p = son[p][u];
            res = res * 2 + u;
        }

    }
    return res;
}

int main()
{
    int n;
    cin >> n;
    
    for(int i = 0; i < n; i ++) cin >> a[i];
    
    int res = 0;
    
    for(int i = 0; i < n; i++)
    {
        insert(a[i]);
        int t = query(a[i]);
        res = max(res, a[i] ^ t);
    }
    
    cout << res << endl;
    
    return 0;
}