_405.java

package com.fishercoder.solutions;

/**
 * 405. Convert a Number to Hexadecimal

 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"

 */
public class _405 {

    public static class Solution1 {
        public String toHex(int num) {
            char[] hexChars =
                new char[] {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
                    'e', 'f'};
            String result = "";
            while (num != 0) {
                result = hexChars[(num & 15)] + result;
                num >>>= 4;
            }
            return result.isEmpty() ? "0" : result;
        }
    }
}