Added solution to find permutations for matrix

YogenRaii · YogenRaii · commit e427c63bd6d3 · 2019-06-21T21:38:49.000-05:00
diff --git a/src/main/java/com/eprogrammerz/examples/algorithm/crackingCoding/ListPermutations.java b/src/main/java/com/eprogrammerz/examples/algorithm/crackingCoding/ListPermutations.java
@@ -11,7 +11,7 @@
 /**
  * Find permutations of list of numbers
  */
-public class Permutations {
+public class ListPermutations {
     public List<List<Integer>> findPermutations(List<Integer> num) {
         List<List<Integer>> permutations = new ArrayList<>();
         findPermutations(num, new ArrayList<>(), permutations);
diff --git a/src/main/java/com/eprogrammerz/examples/algorithm/crackingCoding/MatrixPermutation.java b/src/main/java/com/eprogrammerz/examples/algorithm/crackingCoding/MatrixPermutation.java
@@ -0,0 +1,72 @@
+package com.eprogrammerz.examples.algorithm.crackingCoding;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class MatrixPermutation {
+    public List<int[][]> findMatrixPermutation(int[][] matrix) {
+        int row = matrix.length;
+        int col = matrix[0].length;
+        List<Integer> nums = getList(matrix, row, col);
+
+        ListPermutations listPermutations = new ListPermutations();
+        List<List<Integer>> permutations = listPermutations.findPermutations(nums);
+
+        List<int[][]> matrixPermutations = new ArrayList<>(permutations.size());
+        for (List<Integer> permutation: permutations) {
+            int[][] permMatrix = getMatrix(permutation, row, col);
+            matrixPermutations.add(permMatrix);
+        }
+        return matrixPermutations;
+    }
+
+    @Test
+    public void testFindMatrixPermutation() {
+        int[][] matrix = new int[][] {
+                {1,2},
+                {3,4}
+        };
+        List<int[][]> permutations = findMatrixPermutation(matrix);
+
+        System.out.println("Permutation size: " + permutations.size());
+        for (int[][] perm: permutations) {
+            printMatrix(perm);
+        }
+    }
+
+    private void printMatrix(int[][] matrix) {
+        int row = matrix.length;
+        int col = matrix[0].length;
+
+        for (int r = 0; r < row; r++) {
+            for (int c = 0; c < col; c++) {
+                System.out.print(matrix[r][c] + " ");
+            }
+            System.out.println();
+        }
+        System.out.println();
+    }
+
+    private List<Integer> getList(int[][] matrix, int row, int col) {
+        List<Integer> list = new ArrayList<>(row * col);
+        for (int r = 0; r < row; r++) {
+            for (int c = 0; c < col; c++) {
+                list.add(matrix[r][c]);
+            }
+        }
+        return list;
+    }
+
+    private int[][] getMatrix(List<Integer> list, int row, int col) {
+        int[][] matrix = new int[row][col];
+        int idx = 0;
+        for (int r = 0; r < row; r++) {
+            for (int c = 0; c < col; c++) {
+                matrix[r][c] = list.get(idx++);
+            }
+        }
+        return matrix;
+    }
+}
