Is Minimum Number of Steps to Make Two Strings Anagram II easy or hard?

This problem is classified as Medium on LeetCode but conceptually straightforward once you recognize it as a frequency counting task. The main challenge is identifying that the number of deletions equals the total difference between character counts in the two strings.

Minimum Number of Steps to Make Two Strings Anagram II Python/Java solution

Most Python solutions use a list of size 26 or collections.Counter to track character frequencies. Java solutions typically use an int[26] array or a HashMap . Both implementations iterate through the strings and sum absolute frequency differences to compute the answer.

How to solve Minimum Number of Steps to Make Two Strings Anagram II in O(n)?

Use a frequency counter. Increment counts for each character in the first string and decrement for each character in the second string. After processing both strings, sum the absolute values of the remaining frequency differences. Each difference represents a character that must be deleted.

What is the best approach for Minimum Number of Steps to Make Two Strings Anagram II?

The best approach uses a character frequency count with a fixed array of size 26. Count characters in the first string, subtract counts using the second string, then sum the absolute differences. This runs in O(n) time with O(1) space and is typically the expected interview solution.

Is Minimum Number of Steps to Make Two Strings Anagram II asked at Google/Amazon/Meta?

Anagram and frequency-count problems appear frequently in interviews at companies like Amazon, Google, and Meta. Variations involving character counting, hash maps, and string manipulation are common in coding rounds because they test algorithmic fundamentals and data structure knowledge.

What data structure is used in Minimum Number of Steps to Make Two Strings Anagram II?

The primary data structure is a frequency counter implemented using either an integer array or a hash table. The array approach stores counts for each letter, while the hash table version dynamically tracks character frequencies with constant-time lookups.

What is the time complexity of Minimum Number of Steps to Make Two Strings Anagram II?

The optimal solution runs in O(n) time where n is the combined length of both strings. Each string is scanned once to update frequency counts, and a constant-size array or hash map is processed afterward. Space complexity is O(1) with a fixed alphabet array or O(k) with a hash map.

Description Hints 3 Solution Video 9:06

2186. Minimum Number of Steps to Make Two Strings Anagram II

Medium73.3% acceptance1 company

You are given two strings s and t. In one step, you can append any character to either s or t.

Return the minimum number of steps to make s and t anagrams of each other.

An anagram of a string is a string that contains the same characters with a different (or the same) ordering.

Example 1:

Input: s = "leetcode", t = "coats"
Output: 7
Explanation: 
- In 2 steps, we can append the letters in "as" onto s = "leetcode", forming s = "leetcodeas".
- In 5 steps, we can append the letters in "leede" onto t = "coats", forming t = "coatsleede".
"leetcodeas" and "coatsleede" are now anagrams of each other.
We used a total of 2 + 5 = 7 steps.
It can be shown that there is no way to make them anagrams of each other with less than 7 steps.

Example 2:

Input: s = "night", t = "thing"
Output: 0
Explanation: The given strings are already anagrams of each other. Thus, we do not need any further steps.

Constraints:

1 <= s.length, t.length <= 2 * 10⁵
s and t consist of lowercase English letters.

Asked at 1 company

Wealthfront

Topics

Hints open one at a time

Hint 1

Notice that for anagrams, the order of the letters is irrelevant.

Hint 2

For each letter, we can count its frequency in s and t.

Hint 3

For each letter, its contribution to the answer is the absolute difference between its frequency in s and t.

9:06

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