## Solutions
### [[Hash Table]]
```python
class Solution(object):
def digitSquareSum(self, num):
total = 0
while num > 0:
last_number = num % 10
total += last_number ** 2
num //= 10
return total
def isHappy(self, n):
"""
:type n: int
:rtype: bool
"""
seen = set()
while n != 1:
if n in seen:
return False
else:
seen.add(n)
n = self.digitSquareSum(n)
return True
```
#### Complexity Analysis
- Time complexity is
- Space complexity is