> #include <stdio.h>
> #include <math.h>
> 
> #define INF 0xffffffff
> #define MAX_N 205
> 
> typedef struct { int x, y; } postype;
> 
> int cmp(const void *prev, const void *next)
> {
>   return ((postype *)prev)->x > ((postype *)next)->x ? 1 : -1;
> }
> 
> double euclid_dist(postype a, postype b)
> {
>   return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
> }
> 
> int main()
> {
>   int n;
>   postype p[MAX_N];
>   int i, j;
>   double f[MAX_N][MAX_N];
>   
> 
>   //freopen("input.txt", "r", stdin);
>   //freopen("output.txt", "w", stdout);
>   
>   while (scanf("%d", &n) > 0)
>   {
> 	  for (i = 1; i <= n; i++)
> 	    scanf("%d%d", &p[i].x, &p[i].y);
> 	  qsort(p + 1, n, sizeof(postype), cmp);
> 	  
> 	  f[1][2] = euclid_dist(p[1], p[2]);
> 	  for(j = 3; j <= n; j++)
> 	  {
> 	    for (i = 1; i < j - 1; i++)
> 	      f[i][j] = f[i][j - 1] + euclid_dist(p[j - 1], p[j]);
> 	    
> 	    f[j - 1][j] = INF;
> 	    for (i = 1; i < j - 1; i++)
> 	    {
> 	      double temp = f[i][j - 1] + euclid_dist(p[i], p[j]);
> 	      if (temp < f[j - 1][j])
> 	        f[j - 1][j] = temp;
> 	    }
> 	  }
> 	  
> 	  printf("%.2lf\n", f[n - 1][n] + euclid_dist(p[n - 1], p[n]));
>   }
>   
>   //fclose(stdin);
>   //fclose(stdout);
>   
>   return 0;
> }
我也遇到了相同的情况，估计是浮点精度的问题？