Convert a Number to Hexadecimal

Question

Given an integer, write an algorithm to convert it to hexadecimal. For negative integer, two’s complement method is used.

Note:

All letters in hexadecimal (a-f) must be in lowercase. The hexadecimal string must not contain extra leading 0s. If the number is zero, it is represented by a single zero character '0'; otherwise, the first character in the hexadecimal string will not be the zero character. The given number is guaranteed to fit within the range of a 32-bit signed integer. You must not use any method provided by the library which converts/formats the number to hex directly. Example 1:

Input:
26

Output:
"1a"

Example 2:

Input:
-1

Output:
"ffffffff"

Tags

• Bit

Thought

Reference: https://discuss.leetcode.com/topic/60929/1-liner-in-python

Code

class Solution(object):
    def toHex(self, num):
        """
        :type num: int
        :rtype: str
        """
        def helper(num, h=''):
            return (not num or h[7:]) and h or helper(num / 16, '0123456789abcdef'[num % 16] + h)
        return helper(num)