题目描述：
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"
10进制转16进制。
不断取余数即可，需要考虑到负数和0的情况。
实现代码：
public class Solution {
public string ToHex(int num) {
if(num == 0){
return "0";
}
var n = PositiveNum(num);
var ret = "";
while(n > 0){
var r = n%16;
if(r < 10){
ret = r+ret;
}
else {
var x = (char)((int)'a' +r-10);
//Console.WriteLine(r+","+x);
ret = x + ret;
}
n = n/16;
//Console.WriteLine(ret + ","+n);
}
//ret = n+ret;
return ret;
}
private long PositiveNum(int i){
if(i < 0){
return (long)Math.Pow(2,32) + i;
}
return i;
}
}