hdu 1392 Surround the Trees (凸包)Surround the Trees

Time Limit: 2000/1000 MS

(Java/Others)    Memory Limit: 65536/32768 K

(Java/Others)

Total Submission(s): 7043    Accepted

Submission(s): 2688

Problem Description

There are a lot of trees in an area. A peasant wants

to buy a rope to surround all these trees. So at first he must know the minimal

required length of the rope. However, he does not know how to calculate it. Can

you help him? 

The diameter and length of the trees are omitted, which

means a tree can be seen as a point. The thickness of the rope is also omitted

which means a rope can be seen as a line.

There are no

more than 100 trees.

Input

The input contains one or more data sets. At first

line of each input data set is number of trees in this data set, it is followed

by series of coordinates of the trees. Each coordinate is a positive integer

pair, and each integer is less than 32767. Each pair is separated by

blank.

Zero at line for number of trees terminates the input for your

program.

Output

The minimal length of the rope. The precision should

be 10^-2.

Sample Input

9

12 7

24 9

30 5

41 9

80 7

50 87

22 9

45 1

50 7

Sample Output

243.06

Source

Recommend

Ignatius.L   |   We

have carefully selected several similar problems for you:       

 凸包入門：