issue#1742 (#5638)

Co-authored-by: Yuri Cunha <[email protected]>

program/program/find-the-cofactor-of-a-matrix/FindTheCofactorOfAMatrix.swift

@@ -0,0 +1,92 @@
+import Foundation
+
+class Matrix {
+    let rows: Int
+    let columns: Int
+    var grid: [[Double]]
+
+    init(rows: Int, columns: Int) {
+        self.rows = rows
+        self.columns = columns
+        self.grid = [[Double]](repeating: [Double](repeating: 0.0, count: columns), count: rows)
+    }
+
+    init(grid: [[Double]]) {
+        self.rows = grid.count
+        self.columns = grid[0].count
+        self.grid = grid
+    }
+
+    func printMatrix() {
+        for i in 0..<rows {
+            print(grid[i])
+        }
+    }
+
+    func minorMatrix(row: Int, column: Int) -> Matrix {
+        var minor = [[Double]]()
+
+        for i in 0..<rows {
+            if i != row {
+                var minorRow = [Double]()
+                for j in 0..<columns {
+                    if j != column {
+                        minorRow.append(grid[i][j])
+                    }
+                }
+                minor.append(minorRow)
+            }
+        }
+
+        return Matrix(grid: minor)
+    }
+
+    func determinant() -> Double {
+        guard rows == columns else {
+            fatalError("Matrix must be square to calculate determinant")
+        }
+
+        if rows == 1 {
+            return grid[0][0]
+        }
+
+        if rows == 2 {
+            return grid[0][0] * grid[1][1] - grid[0][1] * grid[1][0]
+        }
+
+        var det = 0.0
+        for i in 0..<columns {
+            let minorMatrix = self.minorMatrix(row: 0, column: i)
+            det += grid[0][i] * pow(-1.0, Double(i)) * minorMatrix.determinant()
+        }
+        return det
+    }
+
+    func cofactorMatrix() -> Matrix? {
+        guard rows == columns else {
+            print("Error: Cofactor matrix can only be calculated for square matrices")
+            return nil
+        }
+
+        var cofactor = [[Double]]()
+        for i in 0..<rows {
+            var cofactorRow = [Double]()
+            for j in 0..<columns {
+                let minorDet = minorMatrix(row: i, column: j).determinant()
+                cofactorRow.append(pow(-1.0, Double(i + j)) * minorDet)
+            }
+            cofactor.append(cofactorRow)
+        }
+
+        return Matrix(grid: cofactor)
+    }
+}
+
+let inputMatrix = Matrix(grid: [[1.0, 2.0, 3.0],
+                                [4.0, 5.0, 6.0],
+                                [7.0, 8.0, 9.0]])
+
+if let cofactorMatrix = inputMatrix.cofactorMatrix() {
+    print("Cofactor Matrix:")
+    cofactorMatrix.printMatrix()
+}