CF1285D Dr. Evil Underscores （分治 + 二进制）

Dr. Evil Underscores

思路：对每位二进制进行判断，如果当前位的二进制都为0或者1，则这个位对答案贡献为0，如果当前为有0有1则这个位对答案贡献(1 << bit)，然后对当前位为0和为1的分成两个集合进行分治，所有答案取min。

#include <cstdio>
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <functional>
#include <set>
#include <vector>
#include <queue>
#include <cstring>
#include <stack>
#include <climits>
 
using namespace std;
 
#define ll long long
#define pb push_back
#define fi first
#define se second

int process(int b, vector<int >& v){
    if(b < 0) return 0;
    vector<int > v0, v1;
    for(auto x : v){
        if((x >> b) & 1) v1.pb(x);
        else v0.pb(x);
    }
    if(v0.size() == 0) return process(b - 1, v1);
    if(v1.size() == 0) return process(b - 1, v0);
    return min(process(b - 1, v0), process(b - 1, v1)) + (1 << b);
}

void solve(){

    int n;
    cin >> n;
    vector<int > a(n);
    for(auto& in : a) cin >> in;
    int ans = process(30, a);
    cout << ans << endl;
}
 
int main(){
    
    // freopen("C:\Users\admin\Desktop\input.txt", "r", stdin);
    // freopen("C:\Users\admin\Desktop\output.txt", "w", stdout);
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    solve();
    
    return 0;
}