Add rotate matrix problem

matrix/rotate_matrix.py

@@ -0,0 +1,91 @@
+# -*- coding: utf-8 -*-
+
+"""
+	In this problem, we want to rotate the matrix elements by 90, 180, 270 (counterclockwise)
+	Discussion in stackoverflow: 
+   https://stackoverflow.com/questions/42519/how-do-you-rotate-a-two-dimensional-array
+"""
+
+
+def rotate_90(matrix: [[]]):
+    """
+    rotate_90([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]])
+    [[4, 8, 12, 16], [3, 7, 11, 15], [2, 6, 10, 14], [1, 5, 9, 13]]
+    """
+
+    transpose(matrix)
+    reverse_row(matrix)
+
+
+def rotate_180(matrix: [[]]):
+    """
+    rotate_180([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]])
+    [[16, 15, 14, 13], [12, 11, 10, 9], [8, 7, 6, 5], [4, 3, 2, 1]]
+    """
+
+    reverse_column(matrix)
+    reverse_row(matrix)
+
+    """
+    OR
+
+    reverse_row(matrix)
+    reverse_column(matrix)
+    """
+
+
+def rotate_270(matrix: [[]]):
+    """
+    rotate_270([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]])
+    [[13, 9, 5, 1], [14, 10, 6, 2], [15, 11, 7, 3], [16, 12, 8, 4]]
+    """
+
+    transpose(matrix)
+    reverse_column(matrix)
+
+    """
+    OR
+
+    reverse_row(matrix)
+    transpose(matrix)
+    """
+
+
+def transpose(matrix: [[]]):
+    matrix[:] = [list(x) for x in zip(*matrix)]
+
+
+def reverse_row(matrix: [[]]):
+    matrix[:] = matrix[::-1]
+
+
+def reverse_column(matrix: [[]]):
+    matrix[:] = [x[::-1] for x in matrix]
+
+
+def print_matrix(matrix: [[]]):
+    for i in matrix:
+        print(*i)
+
+
+if __name__ == '__main__':
+    matrix = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]
+    print("\norigin:\n")
+    print_matrix(matrix)
+    rotate_90(matrix)
+    print("\nrotate 90 counterclockwise:\n")
+    print_matrix(matrix)
+
+    matrix = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]
+    print("\norigin:\n")
+    print_matrix(matrix)
+    rotate_180(matrix)
+    print("\nrotate 180:\n")
+    print_matrix(matrix)
+
+    matrix = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]
+    print("\norigin:\n")
+    print_matrix(matrix)
+    rotate_270(matrix)
+    print("\nrotate 270 counterclockwise:\n")
+    print_matrix(matrix)