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

Note:

1. All letters in hexadecimal ( a-f ) must be in lowercase.
2. The hexadecimal string must not contain extra leading 0 s. 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"

class Solution {
    public String toHex(int num) {
        if (num == 0) return "0";
        char[] map = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};

        String ans = "";
        while (num != 0){
            ans = map[(num & 15)] + ans;
            num = (num >>> 4);
        }

        return ans;
    }
}