Generate All Combinations Sum K in DSA C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does 'Generate All Combinations Sum K' mean?

It means finding all groups of numbers from a list that add up exactly to a target number K.

beginner

Which technique is commonly used to solve 'Generate All Combinations Sum K'?

Backtracking is used to explore all possible number combinations and pick those that sum to K.

intermediate

In backtracking for sum K, why do we sort the input list first?

Sorting helps to stop early when the sum exceeds K and avoid duplicate combinations.

beginner

What is the base case in the recursive backtracking for sum K?

When the current sum equals K, we save the current combination as a valid answer.

intermediate

How do we avoid using the same element multiple times in combinations?

By moving the start index forward in recursion, we ensure each element is used once per combination.

What is the main goal of 'Generate All Combinations Sum K'?

A Sort numbers in ascending order

B Find the largest number less than K

C Find all number groups that add up to K

D Count numbers greater than K

The goal is to find all combinations of numbers that sum exactly to K.

Which method helps explore all possible combinations efficiently?

A Backtracking

B Binary Search

C Dynamic Programming

D Sorting

Backtracking tries all combinations and backtracks when sum exceeds K.

Why do we stop exploring a path when the sum exceeds K?

A Because no further numbers can reduce the sum

B Because sum can become negative

C Because we want the smallest sum

D Because sum equals zero

Once sum is bigger than K, adding more numbers only increases it, so we stop.

How do we avoid duplicate combinations in the result?

A By using only even numbers

B By using a hash map

C By reversing the list

D By sorting and skipping duplicates

Sorting helps detect duplicates and skip them during backtracking.

What happens when the current sum equals K during recursion?

A We reset the sum

B We save the current combination

C We continue adding numbers

D We discard the combination

When sum equals K, the current combination is a valid answer to save.

Explain how backtracking helps find all combinations that sum to K.

Think of exploring paths and going back when a path is not valid.

Describe how sorting the input list improves the combination sum algorithm.

Sorting organizes numbers to make decisions easier.