PAT1004 Counting Leaves

传送门

给一颗树，求出每个层次下叶节点个数

跑一遍树遍历dfs

#include <iostream>
#include<bits/stdc++.h>
#define rep(i,a,n) for(int i=a;i<n;i++)
#define sca(x) scanf("%d",&x)
#define sca2(x,y) scanf("%d%d",&x,&y)
#define scl(x) scanf("%lld",&x)
#define pri(x) printf("%d\n",x)
#define pri2(x,y) printf("%d %d\n",x,y)
#define prl(x) printf("%lld\n",x)
#define ll long long
#define PII pair<int,int>
#define eps 1e-6
#define inf 1e17
#define INF 0x3f3f3f3f
using namespace std;
const int maxn=1e6+5;
vector<int>child[maxn];
int flag[maxn];
int n,m;
int id,cnt,son;
int mx;
int ans[maxn];
void dfs(int root,int depth){
    if(child[root].size()==0){
        ans[depth]++;
        mx=max(mx,depth);
        return ;
    }
    rep(i,0,child[root].size()){
        dfs(child[root][i],depth+1);
    }
}

int main(){
    cin>>n>>m;
    while(m--){
       cin>>id>>cnt;
       rep(i,0,cnt){
        cin>>son;
        child[id].push_back(son);
       }
    }
    mx=-1;
    dfs(1,0);
    rep(i,0,mx+1){
        printf("%d%c",ans[i],i==mx?'\n':' ');
    }
}