As the sum of the digits will finally get a single digit ( 1~9), so I just need to consider whether the 9 numbers are happy numbers or not.

'''

```
def isHappy(self, n):
if n == 1 or n ==7:
return True
elif n in [2, 3, 4, 5, 6, 8, 9]:
return False
else:
squareSum = 0
while n != 0:
squareSum += (n%10) ** 2
n = n // 10
return self.isHappy(squareSum)
```

'''