Is Maximum Number of Balloons easy or hard?

Maximum Number of Balloons is classified as an Easy problem on LeetCode with a moderate acceptance rate around 60%. The difficulty comes from recognizing that some characters in "balloon" appear twice, which requires dividing their counts when calculating the final answer.

How to solve Maximum Number of Balloons in O(n)?

Iterate through the string and count the frequency of each character using an array or hash map. After counting, compute the number of possible "balloon" words by evaluating b, a, l/2, o/2, and n. The smallest of these values is the result. This requires one pass through the string and constant extra memory.

What is the best approach for Maximum Number of Balloons?

The best approach uses character frequency counting. Count how many times each letter appears in the string, then determine how many "balloon" words can be formed by checking the required counts of b, a, l, o, and n. Since l and o appear twice, divide their counts by two. The minimum value among these determines the answer in O(n) time and O(1) space.

Is Maximum Number of Balloons asked at Google/Amazon/Meta?

This problem represents a common string frequency counting pattern frequently used in technical interviews at large tech companies. Variations of character counting and resource allocation problems appear in interviews at companies like Amazon, Google, and Meta when evaluating hash table and string manipulation skills.

What data structure is used in Maximum Number of Balloons?

The primary data structure is a hash table or a fixed-size frequency array. It stores how many times each character appears in the string. Because the input consists of lowercase English letters, many solutions use an integer array of size 26 for constant-time updates and lookups.

What is the time complexity of Maximum Number of Balloons?

The optimal solution runs in O(n) time where n is the length of the input string. The algorithm scans the string once to build character frequencies and then performs a constant number of checks for the letters in "balloon". Space complexity is O(1) because the frequency array size is fixed at 26 letters.

Maximum Number of Balloons Python or Java solution approach?

Both Python and Java implementations follow the same idea: count character frequencies and compute the limiting character among b, a, l/2, o/2, and n. Python often uses collections.Counter, while Java typically uses an int[26] array. Both implementations achieve O(n) time and O(1) space complexity.

Description Hints 2 Solution Video 7:03

1189. Maximum Number of Balloons

Easy64.1% acceptance6 companies

Given a string text, you want to use the characters of text to form as many instances of the word "balloon" as possible.

You can use each character in text at most once. Return the maximum number of instances that can be formed.

Example 1:

Input: text = "nlaebolko"
Output: 1

Example 2:

Input: text = "loonbalxballpoon"
Output: 2

Example 3:

Input: text = "leetcode"
Output: 0

Constraints:

1 <= text.length <= 10⁴
text consists of lower case English letters only.

Note: This question is the same as 2287: Rearrange Characters to Make Target String.

Asked at 6 companies

Wayfair Bloomberg Amazon

Google Microsoft Meta

Topics

Hints open one at a time

Hint 1

Count the frequency of letters in the given string.

Hint 2

Find the letter than can make the minimum number of instances of the word "balloon".

7:03

Still stuck?Read 3 approaches, or watch a walkthrough.

Open solution

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1class Solution:
2    def maxNumberOfBalloons(self, text: str) -> int:
3        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2Case 3

Input

"nlaebolko"

Input

"loonbalxballpoon"

Input

"leetcode"

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