1556 - Calculating Area

Time Limit : 1 Second

Memory Limit : 128 MB

Submission: 186

Solved: 55

Description
       This problem is very straightforward, in a 2-D plane, Give you a polygen, you need calculate its area.

Input
       One integer T indicates the number of test cases

       Each case is started with one integer n which means the number of points of that polygen then n lines followed, each line is a pair of real number x y describe the x-coordinate and y-coordinate of point, points are descriped counter clockwise.

Output
       One real number rounded up to 2 decimal indicates the area of polygen.

sample input
2
4
0 0
1 0
1 1
0 1
3
0 0
1 0
1 1
sample output
1.00
0.50
hint
 
source
The 6th ACM Programming Contest of HUST
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