1934. Black Spot（ｓｐｆａ）

１９３４

水题　ＲＥ了Ｎ久　　后来发现是无向图

  1 #include <iostream>

  2 #include<cstring>

  3 #include<algorithm>

  4 #include<stdlib.h>

  5 #include<vector>

  6 #include<cstdio>

  7 #include<queue>

  8 using namespace std;

  9 #define N 2000010

 10 #define INF 0xfffffff

 11 struct node

 12 {

 13     int u,v,next;

 14     double w;

 15 }ed[N<<1];

 16 int t,head[N],vis[N],dis[N],pa[N],o[N];

 17 double p[N];

 18 int n,m;

 19 void init()

 20 {

 21     t = 0;

 22     memset(head,-1,sizeof(head));

 23 }

 24 void add(int u,int v,int w)

 25 {

 26     ed[t].u = u;

 27     ed[t].v = v;

 28     ed[t].w = w;

 29     ed[t].next = head[u];

 30     head[u] = t++;

 31 }

 32 void spfa(int s,int e)

 33 {

 34     memset(vis,0,sizeof(vis));

 35     int i;

 36     for(i = 1; i <= n ; i++)

 37     {

 38         dis[i] = INF;

 39         p[i] = 0;

 40     }

 41     queue<int>q;

 42     dis[s] = 1;

 43     p[s] = 1;

 44     q.push(s);

 45     while(!q.empty())

 46     {

 47         int u = q.front();

 48         q.pop();

 49         vis[u] = 0;

 50         for(i = head[u] ; i != -1 ; i = ed[i].next)

 51         {

 52             int v = ed[i].v;

 53             double w = ed[i].w;

 54             if(dis[v]>=dis[u]+1)

 55             {

 56                 if(dis[v]==dis[u]+1)

 57                 {

 58                     if(p[v]<p[u]*w/100.0)

 59                     {

 60                         p[v] = p[u]*w/100.0;

 61                         pa[v] = u;

 62                     }

 63                 }

 64                 else

 65                 {

 66                     dis[v] = dis[u]+1;

 67                     p[v] = p[u]*w/100.0;

 68                     pa[v] = u;

 69                 }

 70                 if(!vis[v])

 71                 {

 72                     vis[v] = 1;

 73                     q.push(v);

 74                 }

 75             }

 76         }

 77     }

 78     printf("%d %lf\n",dis[e],1-p[e]);

 79     int x = pa[e],g=1;

 80     o[g] = e;

 81     while(x!=s)

 82     {

 83         g++;

 84         o[g] = x;

 85         x = pa[x];

 86     }

 87     g++;

 88     o[g] = s;

 89     for(i = g ; i > 1; i--)

 90     printf("%d ",o[i]);

 91     printf("%d\n",o[1]);

 92 }

 93 int main()

 94 {

 95     int i;init();

 96     int a,b;

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

 98     scanf("%d%d",&a,&b);

 99     for(i = 1; i <= m ; i++)

100     {

101         int u,v;

102         double w;

103         scanf("%d%d%lf",&u,&v,&w);

104         add(u,v,100-w);

105         add(v,u,100-w);

106     }

107     spfa(a,b);

108     return 0;

109 }

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