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Number to Hexadecimal

Certification: Intermediate Level Accuracy: 0% Submissions: 0 Points: 10

Write a C# program to convert a given integer to its hexadecimal representation without using built-in methods like ToString("X"). For negative integers, use the two's complement method and output the result as a 32-bit representation.

Example 1
    
  
  • Input: num = 26
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  • Output: "1a"
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  • Explanation: 
    
      
      
    • 26 in decimal equals 1a in hexadecimal.
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Example 2
    
  
  • Input: num = -1
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  • Output: "ffffffff"
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  • Explanation: 
    
      
      
    • -1 in two's complement 32-bit representation is all 1's, which in hexadecimal is "ffffffff".
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Constraints
    
  
  • -2^31 ≤ num ≤ 2^31 - 1
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  • Time Complexity: O(log n), where n is the input number
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  • Space Complexity: O(1) not counting the output string
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  • You cannot use built-in methods to directly convert the number to hexadecimal
    •
Bitwise OperationsTech MahindraShopify
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Hint
Solution

Solution Hints

    
  
  • Use bitwise operations to extract 4 bits at a time.
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  • Remember that hexadecimal uses characters 0-9 and a-f.
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  • For negative numbers, use the two's complement representation.
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  • Build the result string from right to left, then reverse it.
    •

Steps to solve by this approach:

 Step 1: Handle the special case where the input number is 0, returning "0".
 Step 2: Create an array of hexadecimal characters (0-9, a-f) for lookup.
 Step 3: Initialize a StringBuilder to build the result.
 Step 4: While the number is not zero, extract the last 4 bits using the bitwise AND operation with 15 (which is 1111 in binary).
 Step 5: Convert the extracted 4 bits to their hexadecimal representation using the lookup array, and insert it at the beginning of the result.
 Step 6: Right shift the number by 4 bits to process the next group of 4 bits. Use unsigned right shift to handle negative numbers correctly.
 Step 7: Return the final string built by the StringBuilder.

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