2019 Nanjing network game Robots

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This link: https://blog.csdn.net/weixin_39132605/article/details/100519662

 https://nanti.jisuanke.com/t/41301

DP1 [i] denotes the i n the desired number of days, dp2 [i] n i to represent the desired endurance;

DP1 [u] = Sum (DP1 [i]) / (Du [i] + 1) + DP1 [u] / (Du [i] + 1) + 1;

dp2[u]=sum(dp2[v])/(du[u]+1)+dp2[u]/(du[u]+1)+dp1[u];

Simplification;

#include <iostream>
#include <cstring>
#include <queue>
#include <vector>
#include <algorithm>
#include <cstdio>
#include <set>
#include <map>
#include <stack>
//#include <tr1/unordered_map>
#include <cmath>
//#include<bits/stdc++.h>
using namespace std;

#define sfi(i) scanf("%d",&i)
#define sfl(i) scanf("%I64d",&i)
#define sfs(i) scanf("%s",(i))
#define pri(i) printf("%d\n",i)
#define prl(i) printf("%I64d\n",i)
#define sff(i) scanf("%lf",&i)
#define ll long long
#define ull unsigned long long
#define uint unsigned int
#define mem(x,y) memset(x,y,sizeof(x))
#define INF 0x3f3f3f3f
#define inf 1e18
#define eps 1e-10
#define PI acos(-1.0)
#define lowbit(x) ((x)&(-x))
#define fl() printf("flag\n")
#define MOD(x) ((x%mod)+mod)%mod
#define endl '\n'
#define pb push_back
#define lson (rt<<1)
#define rson (rt<<1|1)
#define FAST_IO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0)

template<typename T>inline void read(T &x)
{
    x=0;
    static int p;p=1;
    static char c;c=getchar();
    while(!isdigit(c)){if(c=='-')p=-1;c=getchar();}
    while(isdigit(c)) {x=(x<<1)+(x<<3)+(c-48);c=getchar();}
    x*=p;
}

//-----------------------------------------------

const int maxn=1e6+9;
const int mod=1e9+7;

double dp1[maxn],dp2[maxn];

bool vis[maxn];

vector<int>g[maxn];
int n,m;
void dfs(int u)
{
    if(vis[u]) return ;

    vis[u]=1;

    dp1[u]=dp2[u]=0;//要先初始,n时也要初始,再下面return

    if(u==n) return ;

    for(int i=0;i<g[u].size();i++)
    {
        int v=g[u][i];
        dfs(v);
        dp1[u]+=dp1[v];
        dp2[u]+=dp2[v];
    }

    int siz=g[u].size();

    dp1[u]+=siz+1;
    dp1[u]/=siz;

    dp2[u]+=(siz+1)*dp1[u];
    dp2[u]/=siz;

}

int main()
{
    //FAST_IO;
    //freopen("input.txt","r",stdin);

    int T;
    scanf("%d",&T);
    while(T--)
    {

        scanf("%d%d",&n,&m);

        for(int i=1;i<=n;i++) g[i].clear(),vis[i]=0;

        for(int i=0;i<m;i++)
        {
            int u,v;
            scanf("%d%d",&u,&v);
            g[u].pb(v);
        }

        dfs(1);

        printf("%.2lf\n",dp2[1]);

    }

    return 0;
}