How do you solve Biggest Single Number on LeetCode?

Biggest Single Number (LeetCode #619) 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: Using a hash map can significantly reduce time complexity.

What is the brute force solution for Biggest Single Number?

The brute force approach for Biggest Single Number is Brute Force, with O(n²) time complexity and O(1) space complexity. In this approach, we will check each number in the table and count how many times it appears. If it appears only once, we will consider it a single number. Finally, we will find the maximum among these single numbers. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Biggest Single Number?

Biggest Single Number uses the following concepts: Database. The recommended patterns to study are: Hash Map, Array.

What are the interview tips for Biggest Single Number?

Always clarify the requirements and edge cases. Think about space vs. time complexity trade-offs. Practice writing SQL queries as they can be tricky in interviews.

What are common mistakes when solving Biggest Single Number?

Not considering duplicates properly. Failing to handle the case where no single numbers exist.

#619

Biggest Single Number

Easy

DatabaseHash MapArray

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)

Using a hash map, we can efficiently count occurrences of each number in a single pass. Then, we can find the maximum single number in a second pass, making this approach much faster.

⚙️

Algorithm

5 steps

1Step 1: Create a hash map to count occurrences of each number.
2Step 2: Traverse the MyNumbers table and populate the hash map with counts.
3Step 3: Initialize a variable to track the maximum single number.
4Step 4: Traverse the hash map to find the maximum key with a count of 1.
5Step 5: If no single number is found, return null; otherwise, return the maximum single number.

solution.py2 lines

1# Full working Python code
2SELECT MAX(num) AS num FROM MyNumbers WHERE num IN (SELECT num FROM MyNumbers GROUP BY num HAVING COUNT(*) = 1);

ℹ

Complexity note: This complexity is linear because we traverse the list of numbers twice — once for counting and once for finding the maximum single number.

1Using a hash map can significantly reduce time complexity.
2Understanding how to count occurrences is crucial for this problem.

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