信息学奥赛一本通：【1342】最短路径问题

Dijkstra，水题。调试花了一小时不到，不熟练。

提交的时候，发现后三个测试点有问题，以为是程序出问题了。结果发现是上限取的不够大。

总而言之就是经验不足。下次注意。

 1 #include <cstdio>
 2 #include <iostream>
 3 #include <algorithm>
 4 #include <cmath>
 5 
 6 using namespace std;
 7 const int Maxn = 10050;
 8 const double Inf = 100000050;
 9 
10 struct Pic{
11     int x,y;
12 }c[Maxn];
13 
14 struct Dijkstra{
15     double d;
16     bool Known;    
17 }Dij[Maxn];
18 
19 double p[Maxn][Maxn];
20 int k,m,n,x,y,s,t,i,j;
21 
22 
23 
24 
25 void dijkstar(int x)
26 {
27     int a,b,i=x,k;
28     int t; 
29     double Min ;
30     
31     for(k=1;k<n;k++)
32     {
33         Min = Inf;
34         t = 0;
35         for(a=1;a<=n;a++)
36             if( Min > Dij[a].d && !Dij[a].Known )
37             {
38                 Min = Dij[a].d;
39                 t = a;
40             }
41         if(t==0) break;
42         Dij[t].Known = true;
43         
44         for(a=1;a<=n;a++)
45             if(p[i][a] )
46                 if(Dij[a].d > Dij[i].d + p[i][a] )
47                     Dij[a].d = Dij[i].d + p[i][a];
48         
49         i = t;
50     }
51 }
52 
53 double dis(int i,int j)
54 {
55     return sqrt((double)pow((c[i].x - c[j].x),2) + pow((double)(c[i].y - c[j].y),2));
56 }
57 
58 int main()
59 {
60 //    FILE *f = fopen("data.txt","r");
61     scanf("%d",&n);
62 //    fscanf(f, "%d", &n);
63     for(k=1;k<=n;k++)
64     {
65         Dij[k].d =Inf;
66         Dij[k].Known = false;
67     }
68     for(k=1;k<=n;k++)
69     {
70         scanf("%d%d",&x,&y);
71 //        fscanf(f,"%d%d",&x,&y);
72         c[k].x = x;
73         c[k].y = y;
74     }
75     
76     scanf("%d",&m);
77 //    fscanf(f,"%d",&m);
78     for(k=1;k<=m;k++)
79     {
80         scanf("%d%d",&i,&j);
81 //        fscanf(f,"%d%d",&i,&j);
82         p[i][j] = p[j][i] = dis(i,j);
83     }
84     
85     scanf("%d%d",&s,&t);
86 //    fscanf(f,"%d%d",&s,&t);
87     Dij[s].d = 0;
88     dijkstar(s);
89     
90     printf("%.2f",Dij[t].d);
91     return 0;
92 }

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