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  • 【leetcode】Happy Number

    题目简述

    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

    解题思路

    按照题目来就好,注意只有以1截止才happy,开始理解错了

    class Solution:
        # @param {integer} n
        # @return {boolean}
        def isHappy(self, n):
            a = []
            #res = 0
            while True:
                res = 0
                for i in str(n):
                    res += int(i) ** 2
                if res == 1:
                    return True
                elif len(a) > 1 and res == a[-1]:
                    return False
                elif res in a:
                    return False
                else:
                    a.append(res)
                    n = res
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  • 原文地址:https://www.cnblogs.com/MrLJC/p/4446816.html
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