问题描述
Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-231, 231 - 1], then return 0.
Assume the environment does not allow you to store 64-bit integers (signed or unsigned).
Example 1:
Input: x = 123
Output: 321
Example 2:
Input: x = -123
Output: -321
Example 3:
Input: x = 120
Output: 21
Example 4:
Input: x = 0
Output: 0
自己写的解法
def reverse(x)
return 0 if x == 0
is_negative = x < 0
a = x.to_s.reverse!.to_i
a = -a if is_negative
return 0 if a > (2**31 - 1) || a < (-2**31)
a
end
将integer转成string然后用reverse方法即可
别人家的解法
def reverse(x)
if x.negative?
x = (x.to_s.reverse!.to_i * -1)
else
x = x.to_s.reverse!.to_i
end
x.bit_length > 31 ? 0 : x
end
别人写的更加简洁，并且使用到了bit_length，negative?等内置方法