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题目
Given a 32-bit signed integer, reverse digits of an integer.
Note:
Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−2^31, 2^31 − 1].
For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.
给定一个32位的有符号整数,将其所有数字反转。
备注:
假设只处理[−2^31, 2^31 − 1]范围内的整数。当反转后的结果溢出时,返回0。
示例:
Example 1:
Input: 123
Output: 321
Example 2:
Input: -123
Output: -321
Example 3:
Input: 120
Output: 21
思路
这道题比较简单,定义一个新的变量,每次将原数的最后一位提取出来,放入到新数的最后一位即可。这样,原数越来越短,新数越来越长,直至原数长度为0。
python代码
def reverse(x):
"""
:type x: int
:rtype: int
"""
result = 0
a = abs(x)
while(a != 0):
pop = a % 10
a = (a - pop) / 10
result = result * 10 + pop
if x > 0 and result < 2**31:
return int(result)
if x < 0 and result <= 2**31:
return -int(result)
return 0
if '__main__' == __name__:
x = -2147483648
print(reverse(x))