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Tested Python solution for LeetCode 246 with 18 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 246 # by problem number
lcpy gen -s strobogrammatic_number # by problem name
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).
Input: num = "69"
Output: true
Input: num = "88"
Output: true
Input: num = "962"
Output: false
1 <= num.length <= 50num consists of only digits.num does not contain any leading zeros except for zero itself.class Solution:
# Time: O(n)
# Space: O(1)
def is_strobogrammatic(self, num: str) -> bool:
rotated = {"0": "0", "1": "1", "8": "8", "6": "9", "9": "6"}
left = 0
right = len(num) - 1
while left <= right:
if num[left] not in rotated or rotated[num[left]] != num[right]:
return False
left += 1
right -= 1
return True
| Time | Space |
|---|---|
| O(n) | O(1) |