Minimum Number of Steps to Make Two Strings Anagram II

Problem Description

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.

Key Insights

• Each character in both strings must match in frequency to form anagrams.
• The difference in frequency for each character determines how many steps (additions) are needed.
• We can utilize a hash table (or frequency array) to count characters in both strings.

Space and Time Complexity

Time Complexity: O(n + m), where n and m are the lengths of strings s and t, respectively.
Space Complexity: O(1), as the frequency count is limited to a fixed number of characters (26 lowercase English letters).

Solution

To solve the problem, we can use a frequency count for each character in both strings. The algorithm follows these steps:

1. Create a frequency count for each character in string s.
2. Create a frequency count for each character in string t.
3. Compute the difference in frequencies for each character from a to z.
4. The total number of steps required is the sum of the absolute differences in frequencies.

This approach effectively counts how many characters need to be added to either string to equalize their frequencies, thereby making them anagrams.

Code Solutions