solution to the interview problem

[avishwak]

No description provided.

[super30admin]

The student's solution demonstrates a good understanding of binary search to solve the problem of finding a missing number in a sorted array. Here are the detailed observations:

1. Correctness: The solution correctly handles the edge cases where the missing number is at the beginning or end of the array. The binary search implementation is correctly structured to find the missing number by comparing the difference between the array elements and their indices.

2. Time Complexity: The solution has a time complexity of O(log n), which is optimal for this problem as it efficiently reduces the search space by half in each iteration.

3. Space Complexity: The space complexity is O(1), as the solution uses only a constant amount of additional space, which is excellent.

4. Code Quality: The code is well-structured and readable. The variable names (lo, hi, mid) are appropriate and the logic is clearly separated into edge case checks and the main binary search loop. However, adding comments to explain the binary search logic could enhance readability further.

5. Efficiency: The solution is efficient, but there is a minor improvement that could be made. The condition hi - lo > 1 ensures the loop exits when there are two elements left, which is correct. However, the final return statement return arr[lo] + 1 assumes that the missing number is always the next number after arr[lo]. While this works for the given example, adding a comment to clarify this assumption would be beneficial.

Potential Edge Cases: The solution handles the edge cases where the missing number is at the start or end of the array. However, it would be good to test with an array where the missing number is in the middle, such as [1, 2, 4, 5, 6], to ensure the binary search logic works correctly in all scenarios.