1657 - Determine if Two Strings are Close - Medium

Problem:

Two strings are considered close if you can attain one from the other using the following operations:

Operation 1: Swap any two existing characters.
- For example, abcde -> aecdb
Operation 2: Transform every occurrence of one existing character into another existing character, and do the same with the other character.
- For example, aacabb -> bbcbaa (all a's turn into b's, and all b's turn into a's)

You can use the operations on either string as many times as necessary.

Given two strings, word1 and word2, return true if word1 and word2 are close, and false otherwise.

Example 1:

Input: word1 = "abc", word2 = "bca" Output: true Explanation: You can attain word2 from word1 in 2 operations. Apply Operation 1: "abc" -> "acb" Apply Operation 1: "acb" -> "bca"

Example 2:

Input: word1 = "a", word2 = "aa" Output: false Explanation: It is impossible to attain word2 from word1, or vice versa, in any number of operations.

Example 3:

Input: word1 = "cabbba", word2 = "abbccc" Output: true Explanation: You can attain word2 from word1 in 3 operations. Apply Operation 1: "cabbba" -> "caabbb" Apply Operation 2: "caabbb" -> "baaccc" Apply Operation 2: "baaccc" -> "abbccc"

Constraints:

1 <= word1.length, word2.length <= 105
word1 and word2 contain only lowercase English letters.

Problem Analysis:

High-Level Strategy:

Calculate the absolute difference in counts for each character using the Counter class. This gives us a dictionary with the count differences.
Sum the absolute differences to get the total steps needed to make the counts of characters in strings s and t equal.

Complexity:

Time Complexity: O(N + M), where N and M are the lengths of strings s and t. We iterate through both strings once to create the counts.
Space Complexity: O(K), where K is the total number of unique characters in both strings. We use additional space to store the counts and differences.

Solutions:

class Solution:
    def closeStrings(self, word1: str, word2: str) -> bool:
        char1 = Counter(word1)
        char2 = Counter(word2)

        num1 = Counter(char1.values())
        num2 = Counter(char2.values())

        return char1 == char2 or (num1 == num2 and set(word1) == set(word2))

Walter Teng.

1657 - Determine if Two Strings are Close - Medium

Problem:

Problem Analysis:

Solutions:

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