Write an algorithm to determine if a number n 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.
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.Return true __if__ n __is a happy number, and__ false __if not__.
Example 1: Input: n = 19 Output: true Explanation: 12 + 92 = 82 82 + 22 = 68 62 + 82 = 100 12 + 02 + 02 = 1 Example 2: Input: n = 2 Output: false
Constraints:
1 <= n <= 231 - 1
- code
class Solution {
public boolean isHappy(int n) {
Set<Integer> seen = new HashSet<>();
while (n != 1){
if (seen.contains(n)) return false;
seen.add(n);
int next = 0;
while (n > 0){
int digit = n % 10;
n = n / 10;
next += digit * digit;
}
n = next;
}
return true;
}
}
- code
class Solution(object):
def isHappy(self, n):
seen = set([n])
while n != 1:
n = sum(int(digit)**2 for digit in str(n))
if n in seen: return False
seen.add(n)
return True
- code
class Solution:
def isHappy(self, n: int) -> bool:
meet = set()
while n:
if n == 1:
return True
if n in meet:
return False
meet.add(n)
next = 0
while n:
next += (n%10) ** 2
n = n//10
n = next