CF1285D Dr. Evil Underscores （分治 + 二进制）

Posted 2020-12-08 ssummerzzz

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。

 1 #include <cstdio>
 2 #include <iostream>
 3 #include <cstdio>
 4 #include <algorithm>
 5 #include <functional>
 6 #include <set>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstring>
10 #include <stack>
11 #include <climits>
12  
13 using namespace std;
14  
15 #define ll long long
16 #define pb push_back
17 #define fi first
18 #define se second
19 
20 int process(int b, vector<int >& v){
21     if(b < 0) return 0;
22     vector<int > v0, v1;
23     for(auto x : v){
24         if((x >> b) & 1) v1.pb(x);
25         else v0.pb(x);
26     }
27     if(v0.size() == 0) return process(b - 1, v1);
28     if(v1.size() == 0) return process(b - 1, v0);
29     return min(process(b - 1, v0), process(b - 1, v1)) + (1 << b);
30 }
31 
32 void solve(){
33 
34     int n;
35     cin >> n;
36     vector<int > a(n);
37     for(auto& in : a) cin >> in;
38     int ans = process(30, a);
39     cout << ans << endl;
40 }
41  
42 int main(){
43     
44     // freopen("C:\Users\admin\Desktop\input.txt", "r", stdin);
45     // freopen("C:\Users\admin\Desktop\output.txt", "w", stdout);
46     ios::sync_with_stdio(false);
47     cin.tie(0);
48     cout.tie(0);
49     solve();
50     
51     return 0;
52 }
53