P1087 FBI树

添加链接描述

#include <bits/stdc++.h>
using namespace std;
int n;
char s[1025];
int Build(int l,int r){
    int mid = (l + r) >> 1;
    if(l != r){
        Build(l,mid);
        Build(mid + 1,r);
    }
    int a = 0, b = 0;
    for(int i = l;i <= r;i++){
        if(s[i] == '0')
            a++;
        else b++;
    }
    if(a && b)
        cout << "F";
    else if(a)
        cout <<"B";
    else
        cout <<"I";
}
int main(){
    scanf("%d",&n);
    scanf("%s",s+1);

    Build(1,(int)pow(2,n));
    return 0;
}