[Leetcode] Happy Number

最新推荐文章于 2025-09-12 17:31:31 发布

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#数据结构与算法

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

Credits:
Special thanks to @mithmatt and @ts for adding this problem and creating all test cases.

新出的easy的题目。

 1 class Solution {
 2 public:
 3     bool isHappy(int n) {
 4         int tmp, dig;
 5         while (n != 4) {
 6             tmp = 0;
 7             while (n > 0) {
 8                 dig = n % 10;
 9                 tmp += dig * dig;
10                 n /= 10;
11             }
12             n = tmp;
13             if (n == 1) return true;
14         }
15         return false;
16     }
17 };