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

超、凢脫俗 2022-06-04 07:42 142阅读 0赞

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;
        }
    };