Leetcode 405. Convert a Number to Hexadecimal

 

405. Convert a Number to Hexadecimal

Easy

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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.

class Solution {
public:
    string toHex(int num) {
        if(num==0)return "0";
        unsigned int newNum=static_cast(num);
        string str="";
        map m;
        char c='a';
        for(int i=10;i<=15;i++)
        {
            m[i]=c++;
        }
        while(newNum)
        {
            int n=newNum%16;
            if(n<10)
            {
                char c=('0'+n);
                str=c+str;
            }
            else
            {
                str=m[n]+str;
            }
            newNum/=16;
        }
        return str;
    }
};

 

 

Example 1:

Input:
26

Output:
"1a"

Example 2:

Input:
-1

Output:
"ffffffff"

Success

Details 

Runtime: 0 ms, faster than 100.00% of C++ online submissions for Convert a Number to Hexadecimal.

Memory Usage: 5.9 MB, less than 100.00% of C++ online submissions forConvert a Number to Hexadecimal.