TYVJ P1933 绿豆蛙的归宿 题解（未完成）

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cmath>
 5 #include<algorithm>
 6 #include<queue>
 7 #include<cstdlib>
 8 #include<iomanip>
 9 #include<cassert>
10 #include<climits>
11 #define maxn 10001
12 #define F(i,j,k) for(int i=j;i<=k;i++)
13 #define M(a,b) memset(a,b,sizeof(a))
14 #define FF(i,j,k) for(int i=j;i>=k;i--)
15 #define inf 0x7fffffff
16 using namespace std;
17 int read(){
18     int x=0,f=1;char ch=getchar();
19     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
20     while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
21     return x*f;
22 }
23 struct edge{
24     int to,w,next;
25 }p[200010];
26 int tot,n;
27 int head[100010];
28 void addedge(int a,int b,int c){
29     p[tot].to=b;
30     p[tot].w=c;
31     p[tot].next=head[a];
32     head[a]=tot++;
33 }
34 double dp[100010];
35 int out[100010],q[100010];
36 int out1[100010];
37 int main()
38 {
39     std::ios::sync_with_stdio(false);//cout<<setiosflags(ios::fixed)<<setprecision(1)<<y;
40 //  freopen("data.in","r",stdin);
41 //  freopen("data.out","w",stdout);
42     int m,a,b,c;
43     cin>>n>>m;
44     M(head,-1);
45     while(m--){
46         cin>>a>>b>>c;
47         addedge(b,a,c);
48         out[a]=++out1[a];
49     }
50     int s=0,e=-1;
51     q[++e]=n;
52     while(s<=e){
53         s++;
54         int u=q[s];
55         for(int i=head[u];i!=-1;i=p[i].next){
56             int v=p[i].to;
57             dp[v]+=(dp[u]+p[i].w)/out[v];
58             if(--out1[v]==0) q[++e]=v;
59         }
60     }
61     cout<<setiosflags(ios::fixed)<<setprecision(2)<<dp[1];
62     cout<<endl;
63     return 0;
64 }