LeetCode Q202: 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

Solution:

	class Solution {
	public:
	bool isHappy(int n) {
	int m[900]={0};
	while(true){
	int sum=0;
	while(n!=0){
	sum+= (n%10)*(n%10);
	n/=10;
	}
	if(m[sum]==1)
	return false;
	if(m[sum]==0){
	m[sum]=1;
	if(sum==1)
	return true;
	}
	n=sum;
	}
	}
	};

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