UVA1347 Tour

John Doe, a skilled pilot, enjoys traveling. While on vacation, he rents a small plane and starts visitingbeautiful places. To save money, John must determine the shortest closed tour that connects hisdestinations. Each destination is represented by a point in the plane pi =< xi, yi >. John uses thefollowing strategy: he starts from the leftmost point, then he goes strictly left to right to the rightmostpoint, and then he goes strictly right back to the starting point. It is known that the points havedistinct x-coordinates.Write a program that, given a set of n points in the plane, computes the shortest closed tour thatconnects the points according to John’s strategy.

Input

The program input is from a text file. Each data set in the file stands for a particular set of points. Foreach set of points the data set contains the number of points, and the point coordinates in ascendingorder of the x coordinate. White spaces can occur freely in input. The input data are correct.

Output

For each set of data, your program should print the result to the standard output from the beginningof a line. The tour length, a floating-point number with two fractional digits, represents the result.Note: An input/output sample is in the table below. Here there are two data sets. The first onecontains 3 points specified by their x and y coordinates. The second point, for example, has the xcoordinate 2, and the y coordinate 3. The result for each data set is the tour length, (6.47 for the firstdata set in the given example)

Sample Input

3

1 1

2 3

3 1

4

1 1

2 3

3 1

4 2

Sample Output

6.47

7.89

代码：

#include
#include
#include
#define maxn 55
using namespace std;
int n;
double x[maxn],y[maxn];
double jl[maxn][maxn],f[maxn][maxn];
int main()
{
	while(scanf("%d", &n)==1) 
    {
    	for(int i=1;i<=n;i++) scanf("%lf%lf",&x[i],&y[i]);
    	for(int i=1;i<=n;i++)
          for(int j=1;j<=n;j++)
            jl[i][j]=sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));
    	for(int i=n-1;i>=2;i--)
      	  for(int j=1;j