树的遍历——A1004.Counting Leaves(30) 给出一棵树，问每一层有多少叶子节点(可DFS也可BFS)

 

 

#include <bits/stdc++.h>
#include <stdio.h>
#include <stdlib.h>
#include <queue>
using namespace std;
const int maxn = 100010;
struct node{
    //bool leave;//是否是叶节点
    vector<int> child;
}Node[maxn];
void BFS(int root){
    if(Node[root].child.size() == 0){
        printf("1\n");
        return;
    }else{
        printf("0");
    }
    queue<int> que;
    int size = Node[root].child.size();
    for(int i=0;i<size;++i){
        que.push(Node[root].child[i]);
    }
    while(!que.empty()){
        int num = 0;//每一层的叶节点数
        int s = que.size();
        for(int i=0;i<s;++i){
            int first = que.front();
            que.pop();
            if(Node[first].child.size() == 0){
                num++;
            }else{
                int len = Node[first].child.size();
                for(int j =0;j<len;++j){
                    que.push(Node[first].child[j]);
                }
            }
        }
        printf(" %d",num);
    }
}
int main(){
    /*for(int i=0;i<maxn;++i){
        Node[i].leave = true;
    }*/
    int n,m;
    scanf("%d%d",&n,&m);
    for(int i=0;i<m;++i){
        int root,number,children;
        scanf("%d%d",&root,&number);
        //Node[root].leave = false;//为非叶节点
        for(int j=0;j<number;++j){
            int t;
            scanf("%d",&t);
            Node[root].child.push_back(t);
        }
    }
    BFS(1);
    system("pause");
    return 0;
}