Slicker Algorithm in C++

This is a C++ Program to find the area of ploygon using slicker algorithm. The algorithm assumes the usual mathematical convention that positive y points upwards. In computer systems where positive y is downwards (most of them) the easiest thing to do is list the vertices counter-clockwise using the “positive y down” coordinates. The two effects then cancel out to produce a positive area.

Here is source code of the C++ Program to Implement Slicker Algorithm that avoids Triangulation to Find Area of a Polygon. The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.

```
#include <iostream>
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using namespace std;
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const int MAXPOLY = 200;
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double EPSILON = 0.000001;
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class Point
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{
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    private:
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    public:
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        double x, y;
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};
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class Polygon
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{
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    private:
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    public:
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        Point p[MAXPOLY];
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        int n;
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        Polygon()
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        {
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            for (int i = 0; i < MAXPOLY; i++)

                Point p[i];// = new Point();

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        }
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};
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double area(Polygon p)
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{
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    double total = 0;
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    for (int i = 0; i < p.n; i++)
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    {
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        int j = (i + 1) % p.n;
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        total += (p.p[i].x * p.p[j].y) - (p.p[j].x * p.p[i].y);

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    }
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    return total / 2;
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}
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int main(int argc, char **argv)
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{
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    Polygon p;
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    cout << "Enter the number of points in Polygon: ";

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    cin >> p.n;
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    cout << "Enter the coordinates of each point: <x> <y>";

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    for (int i = 0; i < p.n; i++)
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    {
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        cin >> p.p[i].x;
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        cin >> p.p[i].y;
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    }
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    double a = area(p);
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    if (a > 0)
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        cout << "The Area of Polygon with " << (p.n)

                << " points using Slicker Algorithm is : " << a;

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    else
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        cout << "The Area of Polygon with " << p.n

                << " points using Slicker Algorithm is : " << (a * -1);

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}
```

Output:

$ g++ PloygonAreaSlickerAlgo.cpp
$ a.out
 
Enter the number of points in Polygon: 4
Enter the coordinates of each point: <x> <y>
1 1
1 6
6 6
6 1
The Area of Polygon with 4 points using Slicker Algorithm is : 25
 
Enter the number of points in Polygon: 
5
Enter the coordinates of each point: <x> <y>
1 2
4 5
9 8
3 2
1 5
The Area of Polygon with 5points using Slicker Algorithm is : 6.0
------------------
(program exited with code: 0)
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