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:
- All letters in hexadecimal (
a-f
) must be in lowercase. - The hexadecimal string must not contain extra leading
0
s. 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"
分析:将一个整数的二进制补码表示转化成对应十六进制的表示形式。正整数的补码就是它本身的原码表示,负整数的补码为它对应的正数的原码取反后加1。得到最终的二进制补码后,每次取出它的后4位表示的数,可以通过将它和0xF相与,也可以将它对16取模,取完右移四位,直到原数被被移位为0。