[patl2-020]功夫传人

解题关键：dfs的简单应用，需要注意类型double与int

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cstdlib>
#include<iostream>
#include<cmath>
#define maxn 100002
using namespace std;
typedef long long ll;
int n;
double z,r;
int vis[maxn];
int cnt=0,head[maxn];
struct edge{
    int to,nxt;
}e[maxn];
void add_edge(int u,int v){
    e[cnt].to=v;
    e[cnt].nxt=head[u];
    head[u]=cnt++;
}

double dfs(int u,double val){
    if(vis[u]){
        val*=vis[u];
        return val;
    }
    double res=0;
    val*=r;
    for(int i=head[u];i!=-1;i=e[i].nxt){
        int v=e[i].to;
        res+=dfs(v,val);
    }
    return res;
}

int main(){
    memset(head, -1, sizeof head);
    cin>>n>>z>>r;
    r=1-0.01*r;
    for(int i=0;i<n;i++){
        int tmp,t2;
        cin>>tmp;
        if(tmp==0){
            cin>>t2;
            vis[i]=t2;
        }else{
            for(int j=0;j<tmp;j++){
                int t;
                cin>>t;
                add_edge(i,t);
            }
        }
    }
    printf("%d
",(int)dfs(0,z));
    return 0;
}