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

注意三目运算符别写错了。

class Solution {
    public String toHex(int num) {
        if (num == 0) {
            return "0";
        }
        
        StringBuilder sb = new StringBuilder();
        while (num != 0) {
            int x = num & 0xf;
            sb.insert(0, x < 10 ? x + "" : (char) ('a' + x - 10));
            num >>>= 4;
        }
        
        return sb.toString();
    }
}