【PTA-A】1004 Counting Leaves (30 分)（树、DFS、BFS）

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.

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

1.DFS 

#include<iostream>
#include<cmath>
#include<vector>
#include<algorithm>
using namespace std;
const int MAXN = 110;
vector<int> child[MAXN];
int leaf[MAXN] = { 0 };
int max_h = 1;
void DFS(int root, int h) {
	max_h = max(h, max_h);
	if (child[root].size() == 0) {
		leaf[h]++;
		return;
	}
	for (int i = 0; i < child[root].size(); i++) {
		DFS(child[root][i], h + 1);
	}
}
int main() {
	int n, m;
	cin >> n >> m;
	int p, temp, c;
	for (int i = 0; i < m; i++) {
		scanf("%d %d", &p, &temp);
		for (int j = 0; j < temp; j++) {
			scanf("%d", &c);
			child[p].push_back(c);
		}
	}
	DFS(1, 1);
	cout << leaf[1];
	for (int i = 2; i <= max_h; i++) {
		cout << " " << leaf[i];
	}
	return 0;
}

 2.BFS

#include<iostream>
#include<algorithm>
#include<vector>
#include<queue>
using namespace std;
const int MAXN = 110;
vector<int> child[MAXN];
int h[MAXN] = { 0 };
int leaf[MAXN] = { 0 };
int max_h = 0;
void BFS() {
	queue<int> q;
	q.push(1);
	while (!q.empty()) {
		int id = q.front();
		q.pop();
		max_h = max(h[id], max_h);
		if (child[id].size() == 0) {
			leaf[h[id]]++;
		}
		for (int i = 0; i < child[id].size(); i++) {
			h[child[id][i]] = h[id] + 1;
			q.push(child[id][i]);
		}
	}

}
int main() {
	int n, m;
	cin >> n >> m;
	int p, temp, c;
	for (int i = 0; i < m; i++) {
		scanf("%d %d", &p, &temp);
		for (int j = 0; j < temp; j++) {
			scanf("%d", &c);
			child[p].push_back(c);
		}
	}
	h[1] = 1;
	BFS();
	cout << leaf[1];
	for (int i = 2; i <= max_h; i++) {
		cout << " " << leaf[i];
	}
	return 0;
}