一段OJ运行超时代码，请各位指点一下

https://pintia.cn/problem-sets/994805342720868352/problems/994805376476626944
题目链接如下，利用bfs却出现了超时的问题，求助。。。

#include<iostream>
#include<stdlib.h>
#include<stdio.h>
#include<vector>
#include<queue>
#include<algorithm>
#include<math.h>
using namespace std;
using std::vector;
using std::queue;
const int maxn=100010;
struct node{
    double data;
    vector<int>child;
    int layer;
}Node[maxn];
int n;
double p,r;

bool cmp(node a,node b){
    return a.layer>b.layer;
}

void BFS(int x){
    int layer=-1;
    queue<int>q;
    q.push(x);
    while(!q.empty()){
        layer++;
        int length=q.size();
        for(int i=0;i<length;i++){
            int index=q.front();
            q.pop();
            Node[index].layer=layer;
            for(int j=0;j<Node[index].child.size();j++){
                q.push(Node[index].child[j]);
            }
        }
    }
}
int main(){
    int root;
    int mem;
    scanf("%d%lf%lf",&n,&p,&r);
    for(int i=0;i<n;i++){
        scanf("%d",&mem);
        if(mem!=-1){
            //如果不是根节点
            Node[mem].child.push_back(i);
        }else{
            root=i;
        }
    }
    BFS(root);
    sort(Node,Node+n,cmp);
    int layer=Node[0].layer;
    int sum=0;
    for(int i=0;i<n;i++){
        if(Node[i].layer==layer)
            sum++;
    }
    printf("%.2f %d",p*pow(1+r/100,layer),sum);
    system("pause");
    return 0;
}

https://www.liuchuo.net/archives/2465
http://blog.sina.com.cn/s/blog_6a9222920102xcta.html