Create flipping-an-image.py

kamyu104 · kamyu104 · commit c35abbb6d58e · 2018-05-13T23:31:29.000+08:00
diff --git a/Python/flipping-an-image.py b/Python/flipping-an-image.py
@@ -0,0 +1,47 @@
+# Time:  O(n)
+# Space: O(1)
+
+# Given a binary matrix A, we want to flip the image horizontally,
+# then invert it, and return the resulting image.
+#
+# To flip an image horizontally means that each row of the image is reversed.
+# For example, flipping [1, 1, 0] horizontally results in [0, 1, 1].
+#
+# To invert an image means that each 0 is replaced by 1, and each 1 is
+# replaced by 0.
+# For example, inverting [0, 1, 1] results in [1, 0, 0].
+#
+# Example 1:
+#
+# Input: [[1,1,0],[1,0,1],[0,0,0]]
+# Output: [[1,0,0],[0,1,0],[1,1,1]]
+# Explanation: First reverse each row: [[0,1,1],[1,0,1],[0,0,0]].
+# Then, invert the image: [[1,0,0],[0,1,0],[1,1,1]]
+# Example 2:
+#
+# Input: [[1,1,0,0],[1,0,0,1],[0,1,1,1],[1,0,1,0]]
+# Output: [[1,1,0,0],[0,1,1,0],[0,0,0,1],[1,0,1,0]]
+# Explanation: First reverse each row:
+#              [[0,0,1,1],[1,0,0,1],[1,1,1,0],[0,1,0,1]].
+# Then invert the image: [[1,1,0,0],[0,1,1,0],[0,0,0,1],[1,0,1,0]]
+#
+# Notes:
+# 1. 1 <= A.length = A[0].length <= 20
+# 2. 0 <= A[i][j] <= 1
+
+try:
+    xrange          # Python 2
+except NameError:
+    xrange = range  # Python 3
+
+
+class Solution(object):
+    def flipAndInvertImage(self, A):
+        """
+        :type A: List[List[int]]
+        :rtype: List[List[int]]
+        """
+        for row in A:
+            for i in xrange((len(row)+1) // 2):
+                row[i], row[~i] = row[~i] ^ 1, row[i] ^ 1
+        return A
