202. Happy Number #

题目 #

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 1:

Input: 19
Output: true
Explanation: 
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1

题目大意 #

判断一个数字是否是“快乐数字”，“快乐数字”的定义是，不断的把这个数字的每个数字的平方和加起来，反复的加，最终如果能有结果是 1，则是“快乐数字”，如果不能得到一，出现了循环，则输出 false。

解题思路 #

按照题意要求做即可。

代码 #

package leetcode

func isHappy(n int) bool {
	record := map[int]int{}
	for n != 1 {
		record[n] = n
		n = getSquareOfDigits(n)
		for _, previous := range record {
			if n == previous {
				return false
			}
		}
	}
	return true
}

func getSquareOfDigits(n int) int {
	squareOfDigits := 0
	temporary := n
	for temporary != 0 {
		remainder := temporary % 10
		squareOfDigits += remainder * remainder
		temporary /= 10
	}
	return squareOfDigits
}