Recall & Review
beginner
What does the problem 'Generate All Combinations Sum K' ask you to find?
It asks to find all unique combinations of numbers from a given list that add up exactly to a target sum K.
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beginner
Which algorithmic technique is commonly used to solve 'Generate All Combinations Sum K'?
Backtracking is commonly used because it explores all possible combinations and abandons paths that exceed the target sum.
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intermediate
In backtracking for combinations sum K, why do we sort the input array first?
Sorting helps to stop early when the current number exceeds the remaining sum and to avoid duplicate combinations.
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intermediate
What is the role of the 'start index' in the recursive backtracking function for combinations sum K?
It ensures combinations are built without reusing previous elements and helps avoid duplicates by moving forward in the list.
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advanced
How do you handle duplicates in the input list when generating all combinations that sum to K?
By skipping over numbers that are the same as the previous one at the same recursive level to avoid duplicate combinations.
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What is the first step before starting backtracking in 'Generate All Combinations Sum K'?
✗ Incorrect
Sorting the input array helps to prune the search early and handle duplicates efficiently.
In backtracking, what do you do when the current sum exceeds the target K?
✗ Incorrect
If the sum exceeds K, no need to continue; backtrack to try other combinations.
How do you avoid duplicate combinations in the result?
✗ Incorrect
Skipping duplicates during recursion prevents generating the same combination multiple times.
What does the 'start index' parameter control in the recursive function?
✗ Incorrect
It controls which elements can be chosen next to avoid reusing previous elements.
Which data structure is best to store the current combination during backtracking?
✗ Incorrect
A list or stack is used to keep track of the current combination as elements are added or removed.
Explain how backtracking works to generate all combinations that sum to K.
Think of exploring a tree of choices, going deeper and backtracking when needed.
You got /5 concepts.
Describe how to handle duplicates in the input array when generating combinations that sum to K.
Sorting helps to detect duplicates easily.
You got /3 concepts.