Leetcode #2839: Check if Strings Can be Made Equal With Operations I
In this guide, we solve Leetcode #2839 Check if Strings Can be Made Equal With Operations I in Python and focus on the core idea that makes the solution efficient.
You will see the intuition, the step-by-step method, and a clean Python implementation you can use in interviews.
Problem Statement
You are given two strings s1 and s2, both of length 4, consisting of lowercase English letters. You can apply the following operation on any of the two strings any number of times: Choose any two indices i and j such that j - i = 2, then swap the two characters at those indices in the string.
Quick Facts
- Difficulty: Easy
- Premium: No
- Tags: String
Intuition
We need to scan characters while tracking positions or counts.
A simple state machine keeps the logic precise.
Approach
Iterate through the string once and update the state for each character.
Use a map or array if you need fast lookups.
Steps:
- Iterate through characters.
- Maintain necessary state.
- Build or validate the output.
Example
Input: s1 = "abcd", s2 = "cdab"
Output: true
Explanation: We can do the following operations on s1:
- Choose the indices i = 0, j = 2. The resulting string is s1 = "cbad".
- Choose the indices i = 1, j = 3. The resulting string is s1 = "cdab" = s2.
Python Solution
class Solution:
def canBeEqual(self, s1: str, s2: str) -> bool:
return sorted(s1[::2]) == sorted(s2[::2]) and sorted(s1[1::2]) == sorted(
s2[1::2]
)
Complexity
The time complexity is , and the space complexity is . The space complexity is .
Edge Cases and Pitfalls
Watch for boundary values, empty inputs, and duplicate values where applicable. If the problem involves ordering or constraints, confirm the invariant is preserved at every step.
Summary
This Python solution focuses on the essential structure of the problem and keeps the implementation interview-friendly while meeting the constraints.