Sliding Window on Arrays in DSA C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the sliding window technique in arrays?

It is a method to create a 'window' of fixed size that moves over the array to solve problems efficiently by avoiding repeated work.

intermediate

How does the sliding window technique improve performance compared to a naive approach?

It reduces time complexity by reusing previous computations instead of recalculating for every new window, often changing O(n*k) to O(n).

beginner

In a sliding window of size k, how do you update the sum when moving the window by one position?

Subtract the element leaving the window and add the new element entering the window.

intermediate

What kind of problems can be solved using the sliding window technique?

Problems involving subarrays or substrings like maximum sum of k elements, longest substring without repeating characters, or minimum size subarray sum.

advanced

Explain the difference between fixed-size and variable-size sliding windows.

Fixed-size windows have a constant length moving over the array, while variable-size windows can expand or shrink based on conditions to solve more complex problems.

What is the main advantage of using a sliding window over nested loops for subarray problems?

A It uses more memory to store all subarrays

B It always finds the global maximum

C It reduces time complexity by avoiding repeated calculations

D It sorts the array first

Sliding window avoids recalculating sums or values for overlapping parts, reducing time complexity.

In a fixed-size sliding window of size k, how many elements do you add and remove when the window moves one step?

A Add 1 element, remove 1 element

B Add 0 elements, remove 1 element

C Add 1 element, remove 0 elements

D Add k elements, remove k elements

When the window moves by one, one new element enters and one old element leaves.

Which of these problems is best suited for the sliding window technique?

A Finding the sum of all elements in the array

B Finding the maximum sum of any subarray of size k

C Finding the maximum element in the entire array

D Sorting the array

Sliding window efficiently finds sums or values in subarrays of fixed size.

What does a variable-size sliding window allow you to do that a fixed-size window does not?

A Change the window size dynamically based on conditions

B Move the window backwards

C Sort the window elements

D Skip elements in the array

Variable-size windows expand or shrink to meet problem constraints.

If you want to find the longest substring without repeating characters, which technique is most suitable?

A Binary search

B Fixed-size sliding window

C Sorting

D Sliding window with variable size

Variable-size sliding window adjusts size to avoid repeats.

Describe how the sliding window technique works on arrays and why it is useful.

Think about how you can avoid recalculating sums for every subarray.

Explain the difference between fixed-size and variable-size sliding windows with examples.

Consider problems where window size must adjust to conditions.