1004 Counting Leaves （30 分

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<N<100, the number of nodes in a tree, and M (<N), 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.

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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.

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題目大意：給出一個樹形結構（家譜），輸出每一層的葉子結點的數量。
分析：可使用bfs，dfs，層序遍歷該樹，使用dfs遍歷，用二維數組存儲每個有孩子結點的結點以及他們的孩子，用leaveNodeCount[depth]記錄每一層的葉結點的數量

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#include <iostream>
#include <stdio.h>
#include <vector>
#include <algorithm>
using namespace std;
vector<int> v[100];
int leaveNodeCount[100];
int maxdepth = -1;
void dfs(int index,int depth){
    if(v[index].size() == 0){
        leaveNodeCount[depth]++;
        maxdepth = max(depth, maxdepth);
        return ;
    }
    for(int i = 0; i < v[index].size(); i++)
        dfs(v[index][i],depth+1);
}
int main()
{
    int n,m;
    scanf("%d %d",&n,&m);
    for(int i = 0; i < m; i++){
        int id,k,child;
        scanf("%d %d",&id,&k);
        for(int j = 0; j < k; j++){
            scanf("%d",&child);
            v[id].push_back(child);
        }
    }
    dfs(1,1);
    printf("%d",leaveNodeCount[1]);
    for(int i = 2; i <= maxdepth; i++){
        printf(" %d",leaveNodeCount[i]);
    }
    return 0;
}