CodeVS 1094 FBI树 题解

#include <iostream>#include <cstdio>using namespace std;int N;char s[1024+2];char FBI(int L, int R){    if(L == R){        if(s[L]=='0') {cout << 'B'; return 'B';}        else if(s[L]=='1') {cout << 'I'; return 'I';}    }    int mid = (L+R)/2;    char l, r;    l = FBI(L, mid);    r = FBI(mid+1, R);    if(l == 'B' && r == 'B'){cout << 'B'; return 'B';}    else if(l == 'I' && r == 'I'){cout << 'I'; return 'I';}    else{cout << 'F'; return 'F';}}int main(){    freopen("fbi.in", "r", stdin); freopen("fbi.out", "w", stdout);    cin >> N >> s;    FBI(0, (1<<N)-1);    cout << endl;    fclose(stdin); fclose(stdout); return 0;}