One is this:

```
class Solution(object):
def isPerfectSquare(self, num):
"""
:type num: int
:rtype: bool
"""
newNum = int(num**(0.5))
return newNum**2==num
```

And this:(compare the length)

```
class Solution(object):
def isPerfectSquare(self, num):
"""
:type num: int
:rtype: bool
"""
if (len(str(math.sqrt(num)))-len(str(int(math.sqrt(num))))>2):
return False
return True
```

Third:(maybe binary search is effictive)

```
Binary search:.....
```