LeetCode (24) Happy Number
浏览数：23 /
时间：2015年06月11日
题目描述
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
本题比较简单，题目要求对任意一个正整数，不断各个数位上数字的平方和，若最终收敛为1，则该数字为happy number，否则程序可能从某个数开始陷入循环。这道题目我们只用根据规则进行计算，并使用一个哈希表存储已经出现过的数字即可。
class Solution {
public:
bool isHappy(int n) {
if (n < 1)
return false;
if (n == 1)
return true;
unordered_set<int> showedNums;
showedNums.insert(n);
while(true)
{
int s = 0;
while(n)
{
s += (n % 10) * (n % 10);
n = n / 10;
}
if (s == 1)
return true;
else if (showedNums.find(s) != showedNums.end())
return false;
n = s;
showedNums.insert(s);
}
}
};郑重声明：本站内容如果来自互联网及其他传播媒体，其版权均属原媒体及文章作者所有。转载目的在于传递更多信息及用于网络分享，并不代表本站赞同其观点和对其真实性负责，也不构成任何其他建议。
