Hash Table and Hash Function Quiz
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Questions and Answers

What is the initial state of the trees in the Huffman coding algorithm?

  • There are C trees, each with all characters.
  • There are no trees at the beginning of the algorithm.
  • There are C single-node trees—one for each character. (correct)
  • There are C trees, each with a random character.
  • What is the purpose of the Divide step in the Divide and Conquer algorithm?

  • To solve smaller problems recursively. (correct)
  • To combine the solutions to the subproblems.
  • To solve the original problem directly.
  • To find the base case of the problem.
  • What is the condition to select two trees in the Huffman coding algorithm?

  • The two trees with the same weight.
  • The two trees with the smallest weight, breaking ties arbitrarily. (correct)
  • Any two trees in the forest.
  • The two trees with the highest weight.
  • What is the result of the Huffman coding algorithm?

    <p>One tree, which is the optimal Huffman coding tree.</p> Signup and view all the answers

    What is the weight of a tree in the Huffman coding algorithm?

    <p>The sum of the frequencies of its leaves.</p> Signup and view all the answers

    How are the solutions to the subproblems combined in the Divide and Conquer algorithm?

    <p>They are combined to form the solution to the original problem.</p> Signup and view all the answers

    What is the purpose of the Conquer step in the Divide and Conquer algorithm?

    <p>To combine the solutions to the subproblems.</p> Signup and view all the answers

    What is the role of the base case in the Divide and Conquer algorithm?

    <p>It is an exception to the recursive solution.</p> Signup and view all the answers

    How many times does the Huffman coding algorithm select the two trees with the smallest weight?

    <p>C-1 times.</p> Signup and view all the answers

    What is the main difference between the Huffman coding algorithm and the Divide and Conquer algorithm?

    <p>The type of problems they solve.</p> Signup and view all the answers

    Study Notes

    Hash Table and Hash Function

    • A hash table is a data structure that maps keys to indices of a backing array using a hash function.
    • Linear probing is a collision resolution technique that searches for the next available slot in the array.
    • If the end of the array is reached, the search wraps around to the beginning of the array.
    • Quadratic probing is another collision resolution technique that uses a quadratic formula to find the next available slot.

    Hash Table Examples

    • Example 1: Inserting keys (11, 85, 77, 10, 35) into a hash table with a table size of 10.
    • The hash function is key modulo table size.
    • Collisions are resolved using quadratic probing.
    • Example 2: Inserting keys (99, 28, 88) into a hash table with a table size of 10.
    • The same hash function and collision resolution technique are used.

    Double Hashing

    • Double hashing is a technique that uses two hash functions to probe for an available slot.
    • The first hash function determines the initial index, and the second hash function determines the increment for the probe sequence.
    • The increment should never be zero, and all cells in the table should be probed.

    Quicksort

    • Quicksort is a sorting algorithm that uses a partitioning strategy to divide the array into smaller subarrays.
    • The partitioning strategy involves swapping the pivot element with the last element, and then moving a "wall" of elements smaller than the pivot to the left and a "wall" of elements larger than the pivot to the right.
    • The algorithm repeats the partitioning process until the entire array is sorted.

    External Sorting

    • External sorting is a technique used when the input data does not fit into main memory.
    • Previous algorithms, such as Shellsort and Quicksort, require that the input fit into main memory.

    Dijkstra's Algorithm

    • Dijkstra's algorithm is a graph search algorithm used to find the shortest path between nodes in a graph.

    Huffman's Algorithm

    • Huffman's algorithm is a greedy algorithm used to construct an optimal prefix code.
    • The algorithm maintains a forest of trees, where each tree represents a character in the input data.
    • The algorithm repeatedly selects the two trees of smallest weight, combines them into a new tree, and updates the weights of the remaining trees.

    Divide and Conquer

    • Divide and Conquer is a algorithm design paradigm that breaks down a complex problem into smaller sub-problems.
    • The algorithm solves each sub-problem recursively, and then combines the solutions to the sub-problems to form the solution to the original problem.

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    Test your knowledge of hash tables and hash functions, including collision resolution techniques and probing methods.

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