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feat: add Sublist Search Algorithm (TheAlgorithms#1513)
* feat: add sublist search algorithm * updating DIRECTORY.md * clang-format and clang-tidy fixes for e59bc3b * Update search/sublist_search.cpp header docs Co-authored-by: David Leal <halfpacho@gmail.com> * Update search/sublist_search.cpp docs Co-authored-by: David Leal <halfpacho@gmail.com> * Update docs search/sublist_search.cpp Co-authored-by: David Leal <halfpacho@gmail.com> * Update docs search/sublist_search.cpp Co-authored-by: David Leal <halfpacho@gmail.com> * Update minor docs in search/sublist_search.cpp Co-authored-by: David Leal <halfpacho@gmail.com> * made test function non static Co-authored-by: David Leal <halfpacho@gmail.com> * test docs updated Co-authored-by: David Leal <halfpacho@gmail.com> * namespaces added for search algo, docs added for test cases * [feat/fix/docs]: Perform some necessary changes * clang-format and clang-tidy fixes for 5a02b33 * test cases docs added, merge fixed * clang-format and clang-tidy fixes for be0160b * one liner docs added * clang-format and clang-tidy fixes for 95b362f * some final docs fixes * clang-format and clang-tidy fixes for 798972e * Apply suggestions from code review * Apply suggestions from code review * Apply suggestions from code review * docs updated for one line docs * clang-format and clang-tidy fixes for aebae1d * added one liner docs * clang-format and clang-tidy fixes for f6913b7 * Update search/sublist_search.cpp Co-authored-by: David Leal <halfpacho@gmail.com> * Update search/sublist_search.cpp Co-authored-by: David Leal <halfpacho@gmail.com> * clang-format and clang-tidy fixes for 66d1b87 * Update search/sublist_search.cpp Co-authored-by: David Leal <halfpacho@gmail.com> * Update search/sublist_search.cpp Co-authored-by: David Leal <halfpacho@gmail.com> * Apply suggestions from code review * clang-format and clang-tidy fixes for dc5b0c6 * Apply suggestions from code review * clang-format and clang-tidy fixes for 6436932 * Apply suggestions from code review * clang-format and clang-tidy fixes for 35f39b5 * Update docs search/sublist_search.cpp Co-authored-by: David Leal <halfpacho@gmail.com> Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com> Co-authored-by: David Leal <halfpacho@gmail.com>
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‎DIRECTORY.md

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* [Linear Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/linear_search.cpp)
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* [Median Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/median_search.cpp)
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* [Saddleback Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/saddleback_search.cpp)
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* [Sublist Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/sublist_search.cpp)
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* [Ternary Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/ternary_search.cpp)
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* [Text Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/text_search.cpp)
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‎search/sublist_search.cpp

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/**
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* @file
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* @brief Implementation of the [Sublist Search
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* Algorithm](https://www.geeksforgeeks.org/sublist-search-search-a-linked-list-in-another-list)
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* @details
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*
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* ### Algorithm
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*
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* * Sublist search is used to detect a presence of one list in another list.
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* * Suppose we have a single-node list (let's say the first list), and we
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* want to ensure that the list is present in another list (let's say the
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* second list), then we can perform the sublist search to find it.
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*
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* * For instance, the first list contains these elements: 23 -> 30 -> 41,
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* and the second list contains these elements: 10 -> 15 -> 23 -> 30 -> 41
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* -> 49. At a glance, we see that the first list presents in the second list.
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*
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* ### Working
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*
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* * The sublist search algorithm works by comparing the first element
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* of the first list with the first element of the second list.
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* * If the two values don't match, it goes to the next element of the
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* second list. It does this until the two values match.
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*
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* @author [Nitin Sharma](https://github.com/foo290)
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*/
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#include <cassert> /// for assert
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#include <iostream> /// for IO operations
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#include <vector> /// for std::vector
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/**
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* @namespace search
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* @brief Searching algorithms
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*/
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namespace search {
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/**
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* @namespace sublist_search
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* @brief Functions for the [Sublist
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* Search](https://www.geeksforgeeks.org/sublist-search-search-a-linked-list-in-another-list)
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* implementation
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*/
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namespace sublist_search {
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/**
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* @brief A Node structure representing a single link Node in a linked list
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*/
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struct Node {
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uint32_t data = 0; ///< the key/value of the node
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Node *next{}; ///< pointer to the next node
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};
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/**
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* @brief A simple function to print the linked list
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* @param start The head of the linked list
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* @returns void
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*/
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void printLinkedList(Node *start) {
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while (start != nullptr) {
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std::cout << "->" << start->data;
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start = start->next;
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}
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std::cout << std::endl;
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}
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/**
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* @brief Give a vector of data,
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* it adds each element of vector in the linked list and return the address of
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* head pointer.
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* @param data A vector of "int" containing the data that is supposed to be
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* stored in nodes of linked list.
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* @returns Node* A head pointer to the linked list.
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*/
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Node *makeLinkedList(const std::vector<uint64_t> &data) {
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/// This is used in test cases for rapidly creating linked list with 100+
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/// elements, instead of hard-coding 100 elements in test cases.
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Node *head = nullptr;
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Node *tail = nullptr;
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for (int i : data) {
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Node *node = new Node;
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node->data = i;
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node->next = nullptr;
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if (head == nullptr) {
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head = node;
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tail = node;
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} else {
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tail->next = node;
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tail = tail->next;
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}
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}
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return head;
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}
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/**
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* @brief Main searching function
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* @param sublist A linked list which is supposed to be searched in mainList.
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* @param mainList A linked list in which sublist will be searched.
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* @returns true if the sublist is found
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* @returns false if the sublist is NOT found
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*/
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bool sublistSearch(Node *sublist, Node *mainList) {
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if (sublist == nullptr || mainList == nullptr) {
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return false;
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}
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/// Initialize target pointer to the head node of sublist.
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Node *target_ptr = sublist;
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while (mainList != nullptr) {
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/// Initialize main pointer to the current node of main list.
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Node *main_ptr = mainList;
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while (target_ptr != nullptr) {
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if (main_ptr == nullptr) {
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return false;
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} else if (main_ptr->data == target_ptr->data) {
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/// If the data of target node and main node is equal then move
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/// to the next node of both lists.
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target_ptr = target_ptr->next;
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main_ptr = main_ptr->next;
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} else {
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break;
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}
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}
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if (target_ptr == nullptr) {
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/// Is target pointer becomes null that means the target list is
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/// been traversed without returning false. Which means the sublist
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/// has been found and return ture.
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return true;
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}
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/// set the target pointer again to stating point of target list.
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target_ptr = sublist;
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/// set the main pointer to the next element of the main list and repeat
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/// the algo.
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mainList = mainList->next;
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}
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/// If the main list is exhausted, means sublist does not found, return
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/// false
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return false;
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}
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} // namespace sublist_search
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} // namespace search
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/**
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* @brief class encapsulating the necessary test cases
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*/
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class TestCases {
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private:
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/**
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* @brief A function to print given message on console.
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* @tparam T Type of the given message.
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* @returns void
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* */
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template <typename T>
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void log(T msg) {
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// It's just to avoid writing cout and endl
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std::cout << "[TESTS] : ---> " << msg << std::endl;
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}
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public:
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/**
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* @brief Executes test cases
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* @returns void
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* */
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void runTests() {
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log("Running Tests...");
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testCase_1();
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testCase_2();
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testCase_3();
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log("Test Cases over!");
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std::cout << std::endl;
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}
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/**
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* @brief A test case contains edge case, Only contains one element.
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* @returns void
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* */
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void testCase_1() {
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const bool expectedOutput = true; ///< Expected output of this test
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log("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"
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"~");
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log("This is test case 1 for sublist search Algorithm : ");
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log("Description:");
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log(" EDGE CASE : Only contains one element");
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std::vector<uint64_t> sublistData = {
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6}; ///< Data to make linked list which will be the sublist
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std::vector<uint64_t> mainlistData = {
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2, 5, 6, 7,
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8}; ///< Data to make linked list which will be the main list
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search::sublist_search::Node *sublistLL =
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search::sublist_search::makeLinkedList(
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sublistData); ///< Sublist to be searched
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search::sublist_search::Node *mainlistLL =
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search::sublist_search::makeLinkedList(
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mainlistData); ///< Main list in which sublist is to be
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///< searched
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bool exists = search::sublist_search::sublistSearch(
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sublistLL, mainlistLL); ///< boolean, if sublist exist or not
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log("Checking assert expression...");
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assert(exists == expectedOutput);
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log("Assertion check passed!");
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log("[PASS] : TEST CASE 1 PASS!");
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log("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"
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"~");
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delete (sublistLL);
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delete (mainlistLL);
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}
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/**
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* @brief A test case which contains main list of 100 elements and sublist
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* of 20.
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* @returns void
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* */
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void testCase_2() {
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const bool expectedOutput = true; /// Expected output of this test
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log("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"
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"~");
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log("This is test case 2 for sublist search Algorithm : ");
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log("Description:");
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log(" contains main list of 100 elements and sublist of 20");
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std::vector<uint64_t> sublistData(
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20); ///< Data to make linked list which will be the sublist
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std::vector<uint64_t> mainlistData(
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100); ///< Main list in which sublist is to be searched
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for (int i = 0; i < 100; i++) {
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/// Inserts 100 elements in main list
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mainlistData[i] = i + 1;
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}
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int temp = 0;
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for (int i = 45; i < 65; i++) {
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/// Inserts 20 elements in sublist
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sublistData[temp] = i + 1;
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temp++;
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}
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search::sublist_search::Node *sublistLL =
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search::sublist_search::makeLinkedList(
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sublistData); ///< Sublist to be searched
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search::sublist_search::Node *mainlistLL =
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search::sublist_search::makeLinkedList(
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mainlistData); ///< Main list in which sublist is to be
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///< searched
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bool exists = search::sublist_search::sublistSearch(
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sublistLL, mainlistLL); ///< boolean, if sublist exist or not
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log("Checking assert expression...");
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assert(exists == expectedOutput);
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log("Assertion check passed!");
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log("[PASS] : TEST CASE 2 PASS!");
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log("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"
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"~");
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}
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/**
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* @brief A test case which contains main list of 50 elements and sublist
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* of 20.
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* @returns void
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* */
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void testCase_3() {
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const bool expectedOutput = false; ///< Expected output of this test
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log("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"
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"~");
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log("This is test case 3 for sublist search Algorithm : ");
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log("Description:");
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log(" contains main list of 50 elements and sublist of 20");
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std::vector<uint64_t> sublistData(20); ///< Sublist to be searched
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std::vector<uint64_t> mainlistData(
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50); ///< Main list in which sublist is to be searched
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for (int i = 0; i < 50; i++) {
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/// Inserts 100 elements in main list
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mainlistData.push_back(i + 1);
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}
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for (int i = 45; i < 65; i++) {
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/// Inserts 20 elements in sublist
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sublistData.push_back(i + 1);
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}
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search::sublist_search::Node *sublistLL =
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search::sublist_search::makeLinkedList(
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sublistData); ///< Sublist to be searched
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search::sublist_search::Node *mainlistLL =
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search::sublist_search::makeLinkedList(
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mainlistData); ///< Main list in which sublist is to be
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///< searched
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bool exists = search::sublist_search::sublistSearch(
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sublistLL, mainlistLL); ///< boolean, if sublist exist or not
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log("Checking assert expression...");
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assert(exists == expectedOutput);
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log("Assertion check passed!");
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log("[PASS] : TEST CASE 3 PASS!");
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log("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"
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"~");
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}
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};
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/**
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* @brief Self-test implementations
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* @returns void
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*/
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static void test() {
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TestCases tc;
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tc.runTests();
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}
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/**
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* @brief Main function
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* @param argc commandline argument count (ignored)
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* @param argv commandline array of arguments (ignored)
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* @returns 0 on exit
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*/
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int main(int argc, char *argv[]) {
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test(); // run self-test implementations
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std::vector<uint64_t> mainlistData = {
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2, 5, 6, 7, 8}; ///< Main list in which sublist is to be searched
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std::vector<uint64_t> sublistData = {6, 8}; ///< Sublist to be searched
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search::sublist_search::Node *mainlistLL =
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search::sublist_search::makeLinkedList(mainlistData);
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search::sublist_search::Node *sublistLL =
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search::sublist_search::makeLinkedList(
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sublistData); ///< Main list in which sublist is to be
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///< searched
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bool exists = search::sublist_search::sublistSearch(
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sublistLL,
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mainlistLL); ///< boolean to check if the sublist exists or not
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std::cout << "Sublist: " << std::endl;
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search::sublist_search::printLinkedList(sublistLL);
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std::cout << "Main list: " << std::endl;
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search::sublist_search::printLinkedList(mainlistLL);
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std::cout << std::endl;
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if (exists) {
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std::cout << "[TRUE] - sublist found in main list\n";
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} else {
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std::cout << "[FALSE] - sublist NOT found in main list\n";
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}
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return 0;
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}

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