【LeetCode】202. Happy Number
浏览数：22 /
时间：2015年06月11日
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
Credits:
Special thanks to @mithmatt and @ts for adding this problem and creating all test cases.
循环计算每位数字的平方和，直到出现结果为1(返回true)或者重复(返回false)
class Solution { public: bool isHappy(int n) { unordered_map<int, bool> m; int sum = Helper(n); while(sum != 1) { if(m[sum] == true) return false; m[sum] = true; sum = Helper(sum); } return true; } int Helper(int n) {// sum of the squares of its digits int ret = 0; while(n) { int digit = n%10; n /= 10; ret += (digit*digit); } return ret; } };
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