Happy Number

各种进制的转换，一直是自己的软肋，需要好好整理总结一下。

sum = sum + (n%10)*(n%10);
n = n / 10;
public class Solution {
public boolean isHappy(int n) {
Set<Integer> set = new HashSet<>();
while (n != 1) {
int sum = getSum(n);
if (set.contains(sum)) {
return false;
} else {
set.add(sum);
}
n = sum;
}
return true;
}

private int getSum(int n) {
int sum = 0;
while (n > 0) {
sum = sum + (n%10)*(n%10);
n = n / 10;
}
return sum;
}
}