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Câu hỏi

What do you know about the Big-O notation and can you give some examples with respect to different data structures?

Câu trả lời

Big O notation is a mathematical concept used in computer science to describe the performance or complexity of an algorithm. Specifically, it characterizes the time complexity or space complexity in terms of the size of the input data. Big O notation provides a high-level understanding of the algorithm in terms of its efficiency and scalability, focusing on the worst-case scenario.

Understanding Big O Notation

Big O notation, often written as $$O(f(n))$$, describes the upper limit of the runtime or space requirements of an algorithm as the input size grows towards infinity. It is used to express the worst-case scenario of an algorithm's time or space complexity, ignoring constant factors and lower order terms which are less significant for large input sizes[1][3][5][6].

Examples of Big O Notation in Different Data Structures

  1. Array

    • Access: Accessing an element in an array by index is a constant time operation, $$O(1)$$, because it directly computes the memory address of the element.
    • Search: Searching for an element in an unsorted array requires $$O(n)$$ time in the worst case, as it may need to check every element.
    • Insertion/Deletion: At a specific index can be $$O(n)$$ because it might require shifting elements to maintain order[8][10].
  2. Linked List

    • Access: Accessing an element by index in a linked list is $$O(n)$$, as it requires traversal from the head node to the nth node.
    • Search: Similar to access, searching for an element also takes $$O(n)$$ in the worst case.
    • Insertion/Deletion: Insertion or deletion at a known position in a linked list is $$O(1)$$ if the position is given (like the head of the list), but finding the position adds $$O(n)$$ due to the need for traversal[8].
  3. Binary Search Tree (BST)

    • Access/Search: In a balanced BST, these operations are $$O(\log n)$$ because each step of the search halves th...
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