Reverse Integer
Created: January 16, 2019 by [lek-tin]
Last updated: January 16, 2019
Given a 32-bit signed integer, reverse digits of an integer.
Example 1
Input: 123
Output: 321
Example 2
Input: -123
Output: -321
Example 3
Input: 120
Output: 21
Note
Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231, 231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.
Solution
class Solution(object):
def reverse(self, x):
"""
:type x: int
:rtype: int
"""
if x == "" or x == None:
return x
res = "" if x > 0 else "-"
string = str(abs(x))
for i in range(len(string)-1, -1, -1):
res += string[i]
res = int(res)
if res < -2**31 or res >= 2**31:
return 0
return int(res)
class Solution:
def reverse(self, x: int) -> int:
isNegative = x < 0
x = abs(x)
new_x = 0
while x != 0:
new_x = new_x * 10 + x % 10
x //= 10
# Handles overflow
if new_x < -2**31 or new_x >= 2**31:
return 0
return -new_x if isNegative else new_x