Is It the Same Upside Down

Challenge Difficulty: Medium | Estimated completion time: ~20 minutes

The number 6090609 has a special property: if you turn the number upside down (imagine rotating your screen 180 degrees), you get 6090609 again.

Write a function that takes a string on the digits 0, 6, 9 and returns true if the number is the same upside down or false otherwise.

Examples

sameUpsidedown("6090609")
output = true
 
sameUpsidedown("9669")
output = false
# Becomes 6996 when upside down.
 
sameUpsidedown("9")
output = false
 
sameUpsidedown("0")
output = true
 
sameUpsidedown("6090609")
output = true
 
sameUpsidedown("60906096090609")
output = true
 
sameUpsidedown("966909669")
output = false
# Becomes 699606699 when upside down.
 
sameUpsidedown("96666660999999")
output = false

Solution

Python

def same_upsidedown(number_string: str) -> bool: """Check if number looks the same when rotated 180 degrees. Args: number_string: String of digits (0, 6, 9) Returns: True if same upside down, False otherwise """ upside_down_map = {"0": "0", "6": "9", "9": "6"} reversed_string = number_string[::-1] for index, digit in enumerate(reversed_string): if digit not in upside_down_map: return False if upside_down_map[digit] != number_string[index]: return False return True if __name__ == "__main__": print(same_upsidedown("6090609")) # True print(same_upsidedown("9669")) # False print(same_upsidedown("9")) # False print(same_upsidedown("0")) # True

Output