# Leetcocde 405.Convert a Number to Hexadecimal

## Description

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

Note:

1. All letters in hexadecimal (a-f) must be in lowercase.
2. 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.
3. The given number is guaranteed to fit within the range of a 32-bit signed integer.
4. 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"

## Solution

class Solution {
String hex = "0123456789abcdef";

public String toHex(int num) {
if (num == 0) return "0";
String res = "";
while (num != 0) {
res = hex.charAt(num & 15) + res;
num = num >>> 4;
}
return res;
}
}