Leetcode 2839: Check if Strings Can be Made Equal With Operations I

Input: The input consists of two strings, s1 and s2, each containing 4 lowercase English letters.

Example: s1 = 'abcd', s2 = 'cdab'

Constraints:

• Both s1 and s2 have a length of 4.

• Both strings consist only of lowercase English letters.

Output: Return true if it's possible to make the two strings equal using the described operations, otherwise return false.

Example: true

Constraints:

• The output should be a boolean value indicating whether the strings can be made equal or not.

Goal: The goal is to check if it's possible to transform s1 into s2 using the allowed operations.

Steps:

• Check if s1 is already equal to s2.

• If not, attempt to swap characters at indices (0, 2) and (1, 3).

• If the resulting string matches s2 after any number of swaps, return true.

• If no such transformation is possible, return false.

Goal: The constraints on the input are as follows:

Steps:

• s1 and s2 are of length 4.

• Both strings consist only of lowercase English letters.

Assumptions:

• Only the swap operation between indices (i, j) where j - i = 2 is allowed.

• Both input strings are of the same length (4).

• Input: s1 = 'abcd', s2 = 'cdab'

• Explanation: We can swap characters at indices (0, 2) and (1, 3) to transform s1 into s2.

• Input: s1 = 'abcd', s2 = 'dacb'

• Explanation: No number of swaps can make s1 equal to s2.

Approach: The problem can be solved by checking if it's possible to transform s1 into s2 by performing the allowed swap operations.

Observations:

• We are given that both strings are of length 4, so there are only a limited number of swap operations to check.

• By swapping characters at indices (0, 2) and (1, 3), we should be able to check if the strings can be made equal.

Steps:

• If the strings are already equal, return true.

• If not, swap characters at indices (0, 2) and check if the strings match.

• Next, swap characters at indices (1, 3) and check again.

• If any swap leads to the strings matching, return true; otherwise, return false.

Empty Inputs:

• Since the strings always have a length of 4, empty inputs are not possible.

Large Inputs:

• The problem has a fixed size input (length of 4), so large inputs are not a concern.

Special Values:

• The strings may consist of identical characters or all different characters.

Constraints:

• Ensure that the logic works within the fixed input size.

bool canBeEqual(string s1, string s2) {
    if(s1 == s2) return true;
    
    if(s1[0] != s2[0]) swap(s1[0],s1[2]);
    if(s1 == s2) return true;
    
    if(s1[1] != s2[1]) swap(s1[1],s1[3]);
    if(s1 == s2) return true;
    
    return false;
}

1 : Initialization

bool canBeEqual(string s1, string s2) {

Function definition to check if two strings can be made equal by swapping characters.

2 : Base Case

    if(s1 == s2) return true;

Base case check if both strings are already equal.

3 : Swap Step 1

    if(s1[0] != s2[0]) swap(s1[0],s1[2]);

Checks if the first characters are unequal, swaps the first and third characters of s1.

4 : Base Case

    if(s1 == s2) return true;

Checks again if the strings are now equal after the first swap.

5 : Swap Step 2

    if(s1[1] != s2[1]) swap(s1[1],s1[3]);

Checks if the second characters are unequal, swaps the second and fourth characters of s1.

6 : Base Case

    if(s1 == s2) return true;

Checks again if the strings are now equal after the second swap.

7 : Return

    return false;

Returns false if the strings are still not equal after the swaps.

Best Case: O(1)

Average Case: O(1)

Worst Case: O(1)

Description: The time complexity is constant as the input size is fixed at 4.

Best Case: O(1)

Worst Case: O(1)

Description: The space complexity is constant as we only need a few variables to store the strings.

Leetcode 2839: Check if Strings Can be Made Equal With Operations I

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