leetcode 202. 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:
Input: 19
Output: true
Explanation:
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1
class Solution {
public boolean isHappy(int n) {
int sum =0;
if(n == 1 || n == 7){
return true;
}
else if ( n < 10){
return false;
}
else{
while(n > 0){
sum += (n % 10) * (n % 10);
n = n /10;
}
}
return isHappy(sum);
}
}
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