// 报名算法课第一次自己写代码

算法

打表+贪心+字典树

C++ 代码

#include<bits/stdc++.h>
using namespace std;
const  int N  = 4000000 + 10;
int son[N][2] , cnt[N];
typedef long long ll;
ll idx;
ll j,maxn,me;
char str[N];
ll a[N];
int ki[100010][40],num;
void insert(int *b){
    int p = 0;
    for(int i=0;i<31 ; i++){
        int u = b[i];
        if(!son[p][u]) {
            son[p][u] = ++idx;
        }
        p = son[p][u];
    }
}
ll query(int *b){
    ll maxn =0;
    int p = 0;
    for(int i=0;i<31;i++){
        int u =!b[i] ;
        if(!son[p][u]) {
            u = !u;
            maxn *= 2;
        }
        else{
            maxn = maxn*2 + 1;
        }
        p = son[p][u];
    }
    return maxn;
}
int chai(int index,ll k){
    num = 0;
    for(int i=30;i>=0;i--){
        int h  = k>>i&1;
        ki[index][num++] = h;
    }
    return 0;
}
int main(void){ 
     std::ios::sync_with_stdio(false);
    cin.tie(0);
    int m;
    cin>>m;
    for(int i=0;i<m;i++){
        cin>>a[i];
        chai(i,a[i]);
        insert(ki[i]);
    }
    ll res = 0;
    for(int i=0;i<m;i++){
        res = max(res ,query(ki[i]));
    }

    cout<<res<<endl;
}