[leetcode]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

10进制转16进制，负数自动转成补码+1形式

public class Solution {    public String toHex(int num) {        if(num==0){            return "0";        }      StringBuffer stringBuffer=new StringBuffer();        char[] table={'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};        for(int i=0;i<8&&num!=0;i++){        stringBuffer.insert(0,table[num&15]);        num>>=4;        }return stringBuffer.toString();    }}