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:

  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"

Rust Solution

struct Solution;

#[allow(clippy::wrong_self_convention)]
impl Solution {
    fn to_hex(num: i32) -> String {
        format!("{:x}", num)
    }
}

#[test]
fn test() {
    let num = -1;
    let res = "ffffffff";
    assert_eq!(Solution::to_hex(num), res);
}

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