Create happy-number.py

Author: kamyu104

Python/happy-number.py

@@ -0,0 +1,34 @@
+# Time:  O(k), where k is the steps to be happy number
+# Space: O(k)
+#
+# 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:
+    # @param {integer} n
+    # @return {boolean}
+    def isHappy(self, n):
+        lookup = {}
+        while n != 1 and n not in lookup:
+            lookup[n] = True
+            n = self.nextNumber(n)
+        return n == 1
+    
+    def nextNumber(self, n):
+        new = 0
+        for char in str(n):
+            new += int(char)**2
+        return new