版权声明:转载请声明出处,谢谢配合。 https://blog.csdn.net/zxyoi_dreamer/article/details/82224787
解析:
解析以后再说,现在先刷题。。。
代码:
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define re register
#define gc getchar
#define pc putchar
#define cs const
#define st static
#define db double
inline
ll getint(){
ll num=0;
bool f=1;
char c=gc();
for(;!isdigit(c);c=gc())if(c=='-'){f=0,c=gc();break;}
for(;isdigit(c);c=gc())num=(num<<1)+(num<<3)+(c^48);
return f?num:-num;
}
int last[100001],nxt[200001],to[200001],ecnt;
db w[200001];
int n,m;
db dp[100001];
bool vis[100001];
inline
void addedge(int u,int v,db val){
nxt[++ecnt]=last[u],last[u]=ecnt,to[ecnt]=v,w[ecnt]=val;
}
inline
db go(int u){
if(vis[u])return dp[u];
vis[u]=true;
if(u==n)return dp[n]=0.0000;
dp[u]=0.000000000;
int tot=0;
for(int re e=last[u],v=to[e];e;e=nxt[e],v=to[e]){
dp[u]+=w[e]+go(v);
++tot;
}
return dp[u]/=(db)tot;
}
int main(){
n=getint();
m=getint();
for(int re i=1;i<=m;++i){
int u=getint(),v=getint(),val=getint();
addedge(u,v,val);
}
printf("%.2lf",go(1));
return 0;
}