Leetcode 202 Happy Number
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
设定循环,如果最后无法得到1,必定存在某次情况使得得到的值等于之前生成过的值。
*js的Array没有内置contains/include函数,需要自己添加。
Array.prototype.contains = function (x) { for (var i in this) if (this[i] == x) return true return false } var isHappy = function(n) { var temp = [] var s = n.toString() while (true){ var sum = 0 for (var i=0;i<s.length;i++) sum += s[i]*s[i] if(sum == 1) return true else if (temp.contains(sum)) return false temp.push(sum) s = sum.toString() } }
class Solution(object): def isHappy(self, n): nums = [] while True: a = 0 while n: a += (n%10)*(n%10) n /= 10 if a == 1: return True if a in nums: return False else: nums.append(a) n = a