Question Link:

https://leetcode.com/problems/convert-a-number-to-hexadecimal/

Solution

We convert each 4 bits of the number from lowest bits to higher. The only thing is how to convert a negative integer. According to Two’s Complement, we can convert negative by coding the negation of a positive number:

  1. Invert all the bits of the number
  2. Add one

Implementation

[-] Python code accepted by LeetCode OJ 
class Solution(object):
    def toHex(self, num):
        """
        :type num: int
        :rtype: str
        """
        if num == 0: 
            return "0" 
            
        code = "0123456789abcdef"
        res = ""
        
        # Tow's complement negation
        if num < 0:
            num = (-num ^ 0xffffffff) + 1
        
        # Convert binary to hex
        while num != 0:
            x = num & 0xf
            res = code[x] + res
            num = num >> 4
        
        # Return
        return res