246. Strobogrammatic Number

Given a string num which represents an integer, return true if num is a strobogrammatic number.

A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down).

 

Example 1:

Input: num = "69"
Output: true

Example 2:

Input: num = "88"
Output: true

Example 3:

Input: num = "962"
Output: false

 

Constraints:

• 1 <= num.length <= 50
• num consists of only digits.
• num does not contain any leading zeros except for zero itself.

---

class Solution:
    def isStrobogrammatic(self, num: str) -> bool:
        lp=0
        rp=len(num)-1
        while lp<=rp:
            if num[lp] not in "01869":
                return False
            if num[lp] in "018":
                if num[lp]!=num[rp]:
                    return False
            if num[lp] == "6":
                if num[rp]!="9":
                    return False
            if num[lp] == "9":
                if num[rp]!="6":
                    return False
            lp+=1
            rp-=1
        return True