7.Revere Interger
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.
AC code
import sys
class Solution:
def reverse(self, x: int) -> int:
r = []
flag = 1
if x < 0:
flag = -1
x = abs(x)
while x:
r.append(str(x % 10))
x = x // 10
if r == []:
return 0
id = -1
for i in range(len(r)):
if int(r[i]) > 0:
r = r[i:]
break
x = flag * int(''.join(r))
return x if -2147483648 < x < 2147483647 else 0
或者这样也可以
class Solution:
def reverse(self, x: int) -> int:
r = []
flag = 1
if x < 0:
flag = -1
x = abs(x)
ans = 0
while x:
ans = ans * 10 + x % 10
if -2147483648 < ans < 2147483647:
x = x // 10
else:
return 0
x = flag * ans
return x if -2147483648 < x < 2147483647 else 0
