405.md

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

/**
 * @param {number} num
 * @return {string}
 */
var toHex = function(num) {
    "use strict";
    if (num === 0) {
        return "0";
    }
    let result = "";
    while(num) {
        let digit = num & 15;
        if (digit >= 10) {
            digit = String.fromCharCode("a".charCodeAt() + digit-10);
        } else {
            digit = digit.toString();
        }
        result += digit;
        num = num >>> 4;
    }
    return result.split("").reverse().join("");
};