leetcode-405-Convert-a-Number-to-Hexadecimal

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描述

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:

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Input:
26

Output:
"1a"

Example 2:

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Input:
-1

Output:
"ffffffff"

分析

注意 >>> 和 >> 和区别，>>> 可以用于负数。

解决方案1(Java)

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class Solution {
    public String toHex(int num) {
        char[] hexChar = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
        
        if (num == 0) {
            return "0";
        }
        String result = "";
        while(num != 0) {
            result = hexChar[(num & 15)] + result;
            num = (num >>> 4);
        }
        return result;
    }
}

题目来源