Bitwise AND of Numbers Range/ Happy Number

Author: gavinfish

201 Bitwise AND of Numbers Range.py

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+'''
+Given a range [m, n] where 0 <= m <= n <= 2147483647, return the bitwise AND of all numbers in this range, inclusive.
+
+For example, given the range [5, 7], you should return 4.
+'''
+
+class Solution(object):
+    def rangeBitwiseAnd(self, m, n):
+        """
+        :type m: int
+        :type n: int
+        :rtype: int
+        """
+        while n > m:
+            n &= n - 1
+        return n
+
+
+if __name__ == "__main__":
+    assert Solution().rangeBitwiseAnd(5, 7) == 4
+    assert Solution().rangeBitwiseAnd(7, 15) == 0

202 Happy Number.py

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+'''
+Write an algorithm to determine if a number is "happy".
+
+A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy numbers.
+
+Example: 19 is a happy number
+
+1^2 + 9^2 = 82
+8^2 + 2^2 = 68
+6^2 + 8^2 = 100
+1^2 + 0^2 + 0^2 = 1
+'''
+
+class Solution(object):
+    def isHappy(self, n):
+        """
+        :type n: int
+        :rtype: bool
+        """
+        visited = []
+        while n != 1:
+            if n in visited:
+                return False
+            visited.append(n)
+            n = sum([int(i) ** 2 for i in str(n)])
+        return True
+
+
+if __name__ == "__main__":
+    assert Solution().isHappy(19) == True