solution for rotate matrix

Author: nickolasteixeira

Python/chapter01/1.6 - String Compression/Nick.py

@@ -0,0 +1,45 @@
+#!/usr/bin/python3
+import random
+from pprint import pprint
+
+def build_matrix(w, h, max=10):
+    '''function that builds a matrix with random numbers including 0'''
+    return [[random.randint(0, max) for _ in range(w)] for _ in range(h)]
+
+def rotate_matrix(matrix):
+    '''function that rotates a matrix clockwise'''
+    if (len(matrix) is 0 or len(matrix) is not len(matrix[0])): return False
+    matrix_length = len(matrix)
+    for layer in range(matrix_length//2):
+        first = layer
+        last = matrix_length - 1 - layer
+        for i in range(first, last):
+            offset = i - first
+            top = matrix[first][i]
+
+            ######################
+            #  a  ---------->  d #
+            #  ^               | #
+            #  |               | #
+            #  |               | #
+            #  |               v #
+            #  b <------------ c #
+            #######################
+
+            # top left inherits from bottom bottom left
+            matrix[first][i] = matrix[last - offset][first]
+
+            # bottom left becomes bottom right
+            matrix[last - offset][first] = matrix[last][last - offset]
+
+            # bottom right becomes top right
+            matrix[last][last - offset] = matrix[i][last]
+
+            # top right becomes top left
+            matrix[i][last] = top
+
+if __name__ =='__main__':
+    matrix = build_matrix(5, 5)
+    pprint(matrix)
+    rotate_matrix(matrix)
+    pprint(matrix)