Add area of a polygon defined by a vector of points (#531)

src/math/area_of_polygon.rs

@@ -0,0 +1,94 @@
+/**
+ * @file
+ * @brief Calculate the area of a polygon defined by a vector of points.
+ *
+ * @details
+ * This program provides a function to calculate the area of a polygon defined by a vector of points.
+ * The area is calculated using the formula: A = |Σ((xi - xi-1) * (yi + yi-1))| / 2
+ * where (xi, yi) are the coordinates of the points in the vector.
+ *
+ * @param fig A vector of points defining the polygon.
+ * @return The area of the polygon.
+ *
+ * @author [Gyandeep](https://github.com/Gyan172004)
+ * @see [Wikipedia - Polygon](https://en.wikipedia.org/wiki/Polygon)
+ */
+
+ struct Point {
+    x: f64,
+    y: f64,
+}
+
+/**
+ * Calculate the area of a polygon defined by a vector of points.
+ * @param fig A vector of points defining the polygon.
+ * @return The area of the polygon.
+ */
+
+fn area(fig: &Vec<Point>) -> f64 {
+    let mut res = 0.0;
+
+    for i in 0..fig.len() {
+        let p = if i > 0 {
+            &fig[i - 1]
+        } else {
+            &fig[fig.len() - 1]
+        };
+        let q = &fig[i];
+
+        res += (p.x - q.x) * (p.y + q.y);
+    }
+
+    f64::abs(res) / 2.0
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /**
+     * Test case for calculating the area of a triangle.
+     */
+    #[test]
+    fn test_area_triangle() {
+        let points = vec![
+            Point { x: 0.0, y: 0.0 },
+            Point { x: 1.0, y: 0.0 },
+            Point { x: 0.0, y: 1.0 },
+        ];
+
+        assert_eq!(area(&points), 0.5);
+    }
+
+    /**
+     * Test case for calculating the area of a square.
+     */
+    #[test]
+    fn test_area_square() {
+        let points = vec![
+            Point { x: 0.0, y: 0.0 },
+            Point { x: 1.0, y: 0.0 },
+            Point { x: 1.0, y: 1.0 },
+            Point { x: 0.0, y: 1.0 },
+        ];
+
+        assert_eq!(area(&points), 1.0);
+    }
+
+    /**
+     * Test case for calculating the area of a hexagon.
+     */
+    #[test]
+    fn test_area_hexagon() {
+        let points = vec![
+            Point { x: 0.0, y: 0.0 },
+            Point { x: 1.0, y: 0.0 },
+            Point { x: 1.5, y: 0.866 },
+            Point { x: 1.0, y: 1.732 },
+            Point { x: 0.0, y: 1.732 },
+            Point { x: -0.5, y: 0.866 },
+        ];
+
+        assert_eq!(area(&points), 2.598);
+    }
+}