How do you solve Base 7 on LeetCode?

Base 7 (LeetCode #504) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(n) space complexity. Key insight: Understanding base conversion is crucial for many programming tasks.

What is the brute force solution for Base 7?

The brute force approach for Base 7 is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute-force approach involves repeatedly dividing the number by 7 and collecting the remainders to form the base 7 representation. This method is straightforward but inefficient for larger numbers. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Base 7?

Base 7 uses the following concepts: Math, String. The recommended patterns to study are: Math, String Manipulation.

What are the interview tips for Base 7?

Always clarify edge cases like zero and negative numbers. Think about the efficiency of your solution and how to optimize it. Practice explaining your thought process clearly while coding.

What are common mistakes when solving Base 7?

Forgetting to handle the case when num is 0. Incorrectly managing the sign for negative numbers.

#504

Base 7

Easy

MathStringMathString Manipulation

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

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

💡

Intuition

Time O(n)Space O(n)

The optimal solution leverages a more efficient method of converting the number to base 7 by directly calculating the digits without unnecessary string operations. This reduces both time and space complexity.

⚙️

Algorithm

5 steps

1Step 1: Handle the special case where num is 0 and return '0'.
2Step 2: Determine if the number is negative and store the sign.
3Step 3: Use a loop to divide the number by 7, collecting remainders in a list.
4Step 4: Reverse the list of digits to form the correct base 7 representation.
5Step 5: Convert the list to a string and prepend the sign if necessary.

solution.py15 lines

1# Full working Python code
2
3def base7(num):
4    if num == 0:
5        return '0'
6    sign = ''
7    if num < 0:
8        sign = '-'
9        num = -num
10    digits = []
11    while num > 0:
12        digits.append(str(num % 7))
13        num //= 7
14    return sign + ''.join(reversed(digits))
15

ℹ

Complexity note: The time complexity is O(n) because we are processing each digit of the number once. The space complexity is O(n) due to storing the digits in a list before converting them to a string.

1Understanding base conversion is crucial for many programming tasks.
2Handling negative numbers requires careful consideration of the sign.

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