Finish Matrix.java

Author: faisalnjs

ArrayUtil.java

@@ -0,0 +1,13 @@
+public class ArrayUtil {
+    public static void reverseArray(int[] arr) {
+        int start = 0;
+        int end = arr.length - 1;
+        while (start < end) {
+            int temp = arr[start];
+            arr[start] = arr[end];
+            arr[end] = temp;
+            start++;
+            end--;
+        }
+    }
+}

FourDigitInteger.java

@@ -1,4 +1,3 @@
-import java.util.ArrayList;
 import java.util.Scanner;
 
 public class FourDigitInteger {

Matrix.java

@@ -0,0 +1,51 @@
+public class Matrix {
+    private int[][] mat;
+
+    public Matrix (int[][] m) {
+        mat = m;
+    }
+
+    public void reverseAllRows() {
+        int i;
+        for (i = 0; i < mat.length; i++) {
+            int[] arr = mat[i];
+            ArrayUtil.reverseArray(arr);
+            mat[i] = arr;
+        }
+    }
+
+    public void reverseAllColumns() {
+        int[][] newMatrix = new int[mat.length][mat[0].length];
+        for (int i = 0; i < mat.length; i++) {
+            for (int j = 0; j < mat[i].length; j++) {
+                newMatrix[mat.length - i - 1][j] = mat[i][j];
+            }
+        }
+        mat = newMatrix;
+    }
+
+    public void reverseMatrix() {
+        reverseAllRows();
+        reverseAllColumns();
+    }
+
+    public static void main(String[] args) {
+        int[][] mat = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}};
+        int[][] desiredMat = {{4, 3, 2, 1}, {8, 7, 6, 5}, {12, 11, 10, 9}};
+        Matrix mat1 = new Matrix(mat);
+        mat1.reverseAllRows();
+        System.out.println(mat1.mat[0][1] == desiredMat[0][1]);
+        System.out.println(mat1.mat[2][1] == desiredMat[2][1]);
+        System.out.println(mat1.mat[1][3] == desiredMat[1][3]);
+        int[][] anotherMat = {{1, 2}, {3, 4}, {5, 6}};
+        int[][] anotherDesiredMat = {{6, 5}, {4, 3}, {2, 1}};
+        Matrix mat2 = new Matrix(anotherMat);
+        mat2.reverseMatrix();
+        System.out.println(mat2.mat[0][0] == anotherDesiredMat[0][0]);
+        System.out.println(mat2.mat[0][1] == anotherDesiredMat[0][1]);
+        System.out.println(mat2.mat[1][0] == anotherDesiredMat[1][0]);
+        System.out.println(mat2.mat[1][1] == anotherDesiredMat[1][1]);
+        System.out.println(mat2.mat[2][0] == anotherDesiredMat[2][0]);
+        System.out.println(mat2.mat[2][1] == anotherDesiredMat[2][1]);
+    }
+}