S-Tree (UVa 712) 二叉树

题目：https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=839&page=show_problem&problem=653

思路：当前结点为k，左走则 2k，右走则 2k + 1，得到最后的点，减去前面n层的所有结点，得到的下标对应的0或1就是答案。

/* S-Tree (UVa 712) */
#include <iostream>
#include <cstring>
#include <vector>
using namespace std;

const int maxn = 10;

int n;
char s[1<<maxn], input[maxn];        //输入和查询 
int idx[maxn];                    //每一层对应的变量 xi
vector<char> output;                //输出查询结果 

int solve();

int main(){
    //freopen("input.txt", "r", stdin);
    int cnt = 0;
    while(cin >> n && n != 0){
        memset(s+1, 0, sizeof(s+1));
        memset(idx, 0, sizeof(idx));
        output.clear();
        
        for(int i=1; i<=n; i++){
            char str[3];
            cin >> str;
            idx[i] = str[1] - '0';
        }
        
        int m;
        cin >> s+1 >> m;
        for(int i=1; i<=m; i++){
            cin >> input+1;
            output.push_back(s[solve()]);
        }
        
        cout << "S-Tree #" << ++cnt << ":" << endl;
        for(int i=0; i<m; i++)
            cout << output[i];
        cout << endl << endl;
        
    }
}

int solve(){
    int k = 1;
    for(int i=1; i<=strlen(input+1); i++){
        int t = input[idx[i]] - '0';
        if(t == 0)
            k = 2*k;
        else
            k = 2*k + 1;
    }
    //cout << k - (1<<n) + 1 << endl;
    return (k - (1<<n) + 1);
    
}