Leetcode 405 - Convert a number into Hex

Note:

  • Negative and positive numbers are all store as binary, so we don’t really need to worry about it.
  • Use bitmask 0xf to get the last 4 bits.
  • Use a string ‘0123456789abcdef’ and a num’s Mod with 16 to get the char we want. (That’s smart!)

Question:

Given an integer num, return a string representing its hexadecimal representation. For negative integers, two’s complement method is used.

All the letters in the answer string should be lowercase characters, and there should not be any leading zeros in the answer except for the zero itself.

Note: You are not allowed to use any built-in library method to directly solve this problem.

Example:

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Input: num = -1
Output: "ffffffff"

Code:

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/**
* @param {number} num
* @return {string}
*/
var toHex = function(num) {
if (num === 0) return '0';
let ans = '';
const nums = '0123456789abcdef';
while (num !== 0) {
const last4 = num & 0xf;
ans = nums[last4 % 16] + ans;
num = num >>> 4;
}
return ans;
};