How do you solve Convert a Number to Hexadecimal on LeetCode?

Convert a Number to Hexadecimal (LeetCode #405) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(1) time complexity and O(1) space complexity. Key insight: Understanding two's complement is crucial for handling negative numbers.

What is the brute force solution for Convert a Number to Hexadecimal?

The brute force approach for Convert a Number to Hexadecimal is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute-force approach involves repeatedly dividing the number by 16 and collecting the remainders, which represent the hexadecimal digits. This is a straightforward method but can be inefficient for larger numbers. The optimal Optimal Solution approach improves this to O(1).

What algorithm or data structure is used to solve Convert a Number to Hexadecimal?

Convert a Number to Hexadecimal uses the following concepts: Math, String, Bit Manipulation. The recommended patterns to study are: Bit Manipulation, String Manipulation.

What are the interview tips for Convert a Number to Hexadecimal?

Explain your thought process clearly while coding. Consider edge cases like negative numbers and zero early in your solution. Practice converting numbers manually to hexadecimal to build intuition.

What are common mistakes when solving Convert a Number to Hexadecimal?

Confusing the representation of negative numbers in hexadecimal. Not handling leading zeros correctly in the final output.

#405

Convert a Number to Hexadecimal

Easy

MathStringBit ManipulationBit ManipulationString Manipulation

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(1)
Space	O(1)	O(1)

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Intuition

Time O(1)Space O(1)

The optimal solution efficiently converts the number to hexadecimal using bit manipulation. By using bitwise operations, we can directly extract the hexadecimal digits without needing to perform division repeatedly.

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Algorithm

4 steps

1Step 1: Create a string array to hold hexadecimal characters.
2Step 2: If the number is negative, adjust it using two's complement.
3Step 3: Use a loop to extract each hexadecimal digit using bitwise AND and right shift operations.
4Step 4: Assemble the digits into a string and return it, ensuring no leading zeros.

solution.py10 lines

1# Full working Python code
2
3def toHex(num):
4    if num < 0:
5        num += 2**32
6    hex_chars = '0123456789abcdef'
7    hex_string = ''
8    for i in range(8):
9        hex_string = hex_chars[(num >> (4 * (7 - i))) & 0xf] + hex_string
10    return hex_string.lstrip('0') or '0'

ℹ

Complexity note: The time complexity is O(1) because we are always processing a fixed number of bits (32 bits for a 32-bit integer), and the space complexity is also O(1) as we are not using any additional data structures that grow with input size.

1Understanding two's complement is crucial for handling negative numbers.
2Bitwise operations can significantly optimize performance when converting between number bases.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.