The Falling Leaves UVA - 699 二叉树先序递归练习

题目链接

分析：

从数组中间（根节点对应位置）开始向两边递归，即和二叉树先序遍历建树一样，遇见-1则为空子树return。

很好的递归练习题。

#include <bits/stdc++.h>
using namespace std;
const int maxn = 1000;
int sum[maxn];

bool solve(int pos) {
    int v; cin >> v;
    if(v==-1) return false;//空树
    sum[pos] += v;
    solve(pos-1); solve(pos+1);
    return true;
}

int main() {
    freopen("i.txt","r",stdin);
    freopen("o.txt","w",stdout);
    int rnd = 1,i = 0;
    while(true) {
        if(!solve(maxn/2)) break;
        i = 0;
        while(!sum[i]) i++;
        cout << "Case " << rnd++ << ":\n" << sum[i]; i++;
        while(sum[i]) { cout << " " << sum[i]; i++; }
        cout << "\n\n";
        memset(sum, 0, sizeof(sum));
    }
}