How do you solve Maximum Number of Balloons on LeetCode?

Maximum Number of Balloons (LeetCode #1189) 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: The word 'balloon' requires specific counts of certain letters.

What is the brute force solution for Maximum Number of Balloons?

The brute force approach for Maximum Number of Balloons is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute force approach involves checking how many times we can form the word 'balloon' by iterating through the string and counting the occurrences of each character. This method is straightforward but inefficient. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Maximum Number of Balloons?

Maximum Number of Balloons uses the following concepts: Hash Table, String, Counting. The recommended patterns to study are: Hash Map, Array.

What are the interview tips for Maximum Number of Balloons?

Always clarify the problem statement and constraints. Think about edge cases, such as strings that don't contain any letters from 'balloon'. Discuss your thought process and approach before jumping into coding.

What are common mistakes when solving Maximum Number of Balloons?

Not accounting for the fact that 'l' and 'o' are needed twice. Forgetting to check if a character exists in the string before accessing its count.

#1189

Maximum Number of Balloons

Easy

Hash TableStringCountingHash MapArray

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

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

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Intuition

Time O(n)Space O(n)

The optimal solution uses a frequency count of the characters in the string and calculates how many times we can form the word 'balloon' based on the minimum occurrences of its characters. This is efficient and straightforward.

⚙️

Algorithm

3 steps

1Step 1: Count the frequency of each character in the input string.
2Step 2: For the characters in 'balloon', calculate how many complete sets can be formed based on their counts.
3Step 3: Return the minimum number of complete sets that can be formed.

solution.py9 lines

1# Full working Python code
2from collections import Counter
3
4def maxBalloons(text):
5    count = Counter(text)
6    return min(count['b'], count['a'], count['l'] // 2, count['o'] // 2, count['n'])
7
8# Example usage
9print(maxBalloons('loonbalxballpoon'))  # Output: 2

ℹ

Complexity note: The time complexity is O(n) because we only need to iterate through the string once to count the characters. The space complexity is O(n) due to the storage of character counts.

1The word 'balloon' requires specific counts of certain letters.
2The letters 'l' and 'o' are needed twice, which affects the total count.

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