Ruby On Rails Developer

Step 1: I first attempted a brute-force solution using recursion, where I generated all possible subsequences and checked their sums. However, this approach had an exponential time complexity (O(2^N)), which was inefficient for large values of N.

Step 2: The interviewer asked me to optimize the solution. I then used memoization (Top-Down DP) to store previously computed results and avoid redundant calculations, reducing the time complexity significantly.

Step 3: To further optimize, I implemented Bottom-Up Dynamic Programming (Subset Sum Problem approach) using a 2D DP table, which had a time complexity of O(N * S), making it feasible for larger inputs.

Step 4: The interviewer then asked if I could solve it with space optimization. I optimized it using a 1D DP array, reducing space complexity from O(N * S) to O(S). The interviewer was satisfied with this optimized approach.

Step 1: First, I implemented a simple two-pointer approach to check if the string is a palindrome by comparing characters from both ends.

Step 2: The interviewer then asked what would happen if one character was allowed to be removed. I modified the approach to skip at most one mismatched character and check if the remaining substring forms a palindrome.

Step 3: I implemented a helper function to check if a given substring is a palindrome and used it when a mismatch was found. This reduced the problem to checking two cases:

Skipping the left mismatched character.
Skipping the right mismatched character.