POJ 2502 Subway (Dijkstra 最短路＋建图)

#include <cstdio>
#include <cmath>
#include <cstring>
#include <algorithm>
using namespace std;
int const MAX = 405;
int const INF = 100000000.0;

struct Node
{
    double u, v;
}nd[MAX];

double dis[MAX], e[MAX][MAX];
bool vis[MAX];
int cnt;

double get_dis(double x1, double y1, double x2, double y2)
{
    return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}

void Dijkstra(int v0)
{
    for(int i = 0; i < cnt; i++)
        dis[i] = e[v0][i];
    dis[v0] = 0;
    vis[v0] = true;
    for(int i = 0; i < cnt - 1; i++)
    {
        double mi = INF;
        int u = v0;
        for(int j = 0; j < cnt; j++)
        {
            if(!vis[j] && mi > dis[j])
            {
                u = j;
                mi = dis[j];
            }
        }
        vis[u] = true;
        for(int k = 0; k < cnt; k++)
            if(!vis[k] && dis[k] > dis[u] + e[u][k])
                dis[k] = dis[u] + e[u][k];
    }
}

int main()
{
    memset(vis, false, sizeof(vis));
    memset(e, 0, sizeof(e));
    scanf("%lf %lf %lf %lf", &nd[0].u, &nd[0].v, &nd[1].u, &nd[1].v);
    double u, v;
    int tmp = 2;
    cnt = 2;
    while(scanf("%lf %lf", &u, &v) != EOF)
    {
        if(u == -1.0 && v == -1.0)
        {
            for(int i = tmp; i < cnt - 1; i++)
            {
                double get = get_dis(nd[i].u, nd[i].v, nd[i + 1].u, nd[i + 1].v) / 40000.0;
                e[i][i + 1] = e[i + 1][i] = get;
            }
            tmp = cnt;
            continue;
        }
        nd[cnt].u = u;
        nd[cnt++].v = v;
    }
    for(int i = 0; i < cnt; i++)
        for(int j = i + 1; j < cnt; j++)
            if(e[i][j] == 0)
                e[i][j] = e[j][i] = get_dis(nd[i].u, nd[i].v, nd[j].u, nd[j].v) / 10000.0;
    Dijkstra(0);
    printf("%d\n", (int)(dis[1] * 60.0 + 0.5));
}