最短路径问题(floyd)

http://acm.sdut.edu.cn/sdutoj/problem.php?action=showproblem&problemid=1867

#include<stdio.h>
#include<string.h>
#include<math.h>
const int maxn = 102;
const int INF=1<<28;
double dis[maxn][maxn];
struct node
{
    double x;
    double y;
} f[maxn];//储存每个点的坐标
int n,m;
void init()
{
    for (int i = 0; i <= n; i ++)
    {
        for (int j = 0; j <= n; j ++)
        {
            dis[i][j] = INF;
        }
        dis[i][i] = 0;
    }
}
void floyd()
{
    int i,j,k;
    for (k = 1; k <= n; k ++)
    {
        for (i = 1; i <= n; i ++)
        {
            for (j = 1; j <= n; j ++)
            {
                if(dis[i][j] > dis[i][k] + dis[k][j])//更新距离
                    dis[i][j] = dis[i][k] + dis[k][j];
            }
        }
    }
}
int main()
{
    scanf("%d",&n);
    init();
    for (int i = 1; i <= n; i ++)
    {
        scanf("%lf%lf",&f[i].x,&f[i].y);
    }
    scanf("%d",&m);
    int u,v;
    while(m--)
    {
        scanf("%d%d",&u,&v);
        double d = sqrt((f[u].x-f[v].x)*(f[u].x-f[v].x)+(f[u].y-f[v].y)*(f[u].y-f[v].y));//计算u、v 之间的距离
        if (dis[u][v] > d) // 判断重边
        {
            dis[u][v] = d;
            dis[v][u] = d;
        }
    }
    int s,e;
    scanf("%d%d",&s,&e);
    floyd();
    printf("%.2f
",dis[s][e]);
    return 0;
}