leetcode 405. Convert a Number to Hexadecimal 十进制转化十六进制-蒲公英云

leetcode 405. Convert a Number to Hexadecimal 十进制转化十六进制

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”

这道题题意十分简单，就是做一个十六进制的转换，对于C++直接取值转换即可

代码如下：

#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <string>
#include <climits>
#include <algorithm>
#include <sstream>
#include <bitset>
using namespace std;
class Solution 
{
public:
    string toHex(int num) 
    {
        if (num == 0) 
            return "0";
        const string HEX = "0123456789abcdef";
        string result;
        int count = 0;
        while (num!=0 && count < 8) 
        {
            result = HEX[(num & 0xf)] + result;
            num >>= 4;
            count++;
        }
        return result;
    }
};