PAT1004 Counting Leaves

A family hierarchy is usually presented by a pedigree tree. Your job is to count those family members who have no child.

Input Specification:

Each input file contains one test case. Each case starts with a line containing 0, the number of nodes in a tree, and M (<), the number of non-leaf nodes. Then M lines follow, each in the format:

ID K ID[1] ID[2] ... ID[K]

where ID is a two-digit number representing a given non-leaf node, K is the number of its children, followed by a sequence of two-digit ID's of its children. For the sake of simplicity, let us fix the root ID to be 01.

The input ends with N being 0. That case must NOT be processed.

Output Specification:

For each test case, you are supposed to count those family members who have no child for every seniority level starting from the root. The numbers must be printed in a line, separated by a space, and there must be no extra space at the end of each line.

The sample case represents a tree with only 2 nodes, where 01 is the root and 02 is its only child. Hence on the root 01 level, there is 0 leaf node; and on the next level, there is 1 leaf node. Then we should output 0 1 in a line.

Sample Input:

2 1
01 1 02

Sample Output:

0 1



读题和题意理解都没有问题，打印每层的叶子节点个数。
参考代码：
https://www.liuchuo.net/archives/2229
柳婼姐受我一拜！

#include<iostream>
#include<iomanip>
#include<stdlib.h>
#include<stdio.h>
#include<algorithm>
#include<math.h>
#include<vector>
using namespace std;
vector<int>v[100];
int book[100];
int maxdepth=-1;
void dfs(int index, int depth) {
    //结束条件
    if (v[index].size() == 0) {
        //那层的叶子数+1
        book[depth]++;
        //要统计最大层数，所以需要maxdepth
        maxdepth = max(maxdepth, depth);
        //不往下找了，回溯
        return;
    }
    for (int i = 0; i < v[index].size(); i++) {
        dfs(v[index][i], depth + 1);//往下找
    }
}
int main() {
    int n, m, id, k, c;
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        cin >> id >> k;
        for (int j = 0; j < k; j++) {
            cin >> c;
            v[id].push_back(c);//push_back操作一开始写错了
        }
    }
    dfs(1, 0);
    cout << book[0];
    for (int i = 1; i <= maxdepth; i++)
        cout << " " << book[i];
    system("pause");
    return 0;
}