poj2502（最短路）

Posted 2020-09-12 yijiull

题目连接：http://poj.org/problem?id=2502

用模拟栈试试。。。

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<cmath>
 4 #include<stack>  //用了模拟栈
 5 using namespace std;
 6 const int maxn=210;
 7 const int inf=0x3f3f3f3f;
 8 double x[maxn],y[maxn],dis[maxn];
 9 
10 struct edge
11 {
12     double w;
13     int v,nex;
14 }e[maxn*maxn*2];
15 int head[maxn];
16 int cnt;
17 int sta[maxn*maxn];   //不知道要开多大
18 int ins[maxn];
19 
20 void add(int u,int v,double w)
21 {
22     e[cnt].v=v;
23     e[cnt].w=w;
24     e[cnt].nex=head[u];
25     head[u]=cnt++;
26 }
27 
28 double getdis(int last,int now)
29 {
30     double dx=x[last]-x[now];
31     double dy=y[last]-y[now];
32     return sqrt(dx*dx+dy*dy);
33 }
34 void double_make(int from, int to, double w)
35 {
36     add(from, to, w);
37     add(to, from, w);
38 }
39 void spfa()
40 {
41 
42     int tot=0;
43     dis[0]=0;
44     ins[0]=1;
45     sta[tot++]=0;
46     while(tot)
47     {
48         int x=sta[--tot];
49         ins[x]=0;
50         for(int i=head[x];i!=-1;i=e[i].nex)
51         {
52             int v=e[i].v;
53             double w=e[i].w;
54             if(dis[v]>dis[x]+w)
55             {
56                 dis[v]=dis[x]+w;
57                 if(!ins[v])
58                 {
59                     sta[tot++]=v;
60                     ins[v]=1;
61                 }
62             }
63         }
64     }
65 }
66 int main()
67 {
68    scanf("%lf%lf%lf%lf",&x[0],&y[0],&x[1],&y[1]);
69     memset(head,-1,sizeof(head));
70     cnt=0;
71       int n = 2, last = 0;
72     while (scanf("%lf %lf", &x[n], &y[n])!=EOF)
73     {
74         if (x[n] == -1 && y[n] == -1)
75         {
76             last = 0;
77             continue;
78         }
79         if (last) double_make(last, n, getdis(last, n) * 3.0 / 2000.0); 
80         last = n++;
81     }
82 
83         for(int i=0;i<n;i++)
84             for(int j=i+1;j<n;j++)
85         {
86             double w=getdis(i,j)*3.0/500.0;
87             add(i,j,w);
88             add(j,i,w);
89         }
90          for(int i=0;i<n;i++)
91         {
92         dis[i]=inf;
93         ins[i]=0;
94         }
95         spfa();
96         printf("%.0f\n",round(dis[1]));
97 
98 }