题:https://leetcode.com/problems/convert-a-number-to-hexadecimal/description/
题目
Given an integer, write an algorithm to convert it to hexadecimal. For negative integer, two’s complement method is used.
Note:
All letters in hexadecimal (a-f) must be in lowercase.
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.
The given number is guaranteed to fit within the range of a 32-bit signed integer.
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"
题目大意
将 num 变为 补码形式,然后求其 十六进制的格式。
思路
由于 是 十六进制的,所以可以 直接用 位运算。
同时 是 补发,所以 使用 非符号右移。
class Solution {
static char[] map = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
public String toHex(int num) {
StringBuilder strBuilder = new StringBuilder();
do{
strBuilder.append(map[num & 0b1111]);
num = num>>>4;
}while(num>0);
return strBuilder.reverse().toString()
}
}