[leetcode]Happy Number

最新推荐文章于 2018-12-29 13:26:19 发布

转载最新推荐文章于 2018-12-29 13:26:19 发布 · 120 阅读

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本文介绍了一个简单的算法，用于判断一个正整数是否为快乐数。快乐数是指通过反复将其每位数字平方并求和，最终能得到1的数字。文章提供了一个Python实现的例子。

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

12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1

def isHappy(self, n):
        """
        :type n: int
        :rtype: bool
        """
        seen = set()
        while n not in seen:
            seen.add(n)
            n = sum([int(x) **2 for x in str(n)])
        return n == 1