下落的树叶 （The Falling Leaves UVA

题目描述：

原题：https://vjudge.net/problem/UVA-699

题目思路:

1.依旧二叉树的DFS

2.建树过程中开个数组统计

//紫书源代码WA 

AC代码：

#include <iostream>
#include <cstring>
using namespace std;

const int maxn = 100 ;
int sum[maxn] ;

void buildtree(int val,int p) //建树，p为树根的水平位置 
{
    int vl,vr;
    if(val == -1) return ;
    sum[p] += val ;
    cin >> vl ;
    buildtree(vl,p - 1);
    cin >> vr ;
    buildtree(vr,p + 1);    
} 

int main(int argc, char *argv[])
{
    int k=0,v;
    while(cin >> v && v != -1){
        memset(sum,0,sizeof(sum)) ;
        int pos = maxn/2 ;
        buildtree(v,pos) ;
        int p = 0;
        while(sum[p] == 0) p++ ; //最左边的子叶 
        cout << "Case " << ++k << ":
" << sum[p++];
        while(sum[p] != 0) {
              cout << " " << sum[p];
              p++;
        }
        cout << "

";
    }
    return 0;
}