Merge pull request ephremdeme#145 from ANKITAKHAN/ank

Added trie data structure in C++

Author: Kanhakhatri065

trie data structure/trie.cpp

@@ -0,0 +1,202 @@
+#include <iostream>
+
+// define character size
+#define CHAR_SIZE 128
+
+// A Class representing a Trie node
+class Trie
+{
+public:
+bool isLeaf;
+Trie* character[CHAR_SIZE];
+
+// Constructor
+Trie()
+{
+this->isLeaf = false;
+
+for (int i = 0; i < CHAR_SIZE; i++)
+this->character[i] = nullptr;
+}
+
+void insert(std::string);
+bool deletion(Trie*&, std::string);
+bool search(std::string);
+bool haveChildren(Trie const*);
+};
+
+// Iterative function to insert a key in the Trie
+void Trie::insert(std::string key)
+{
+// start from root node
+Trie* curr = this;
+for (int i = 0; i < key.length(); i++)
+{
+// create a new node if path doesn't exists
+if (curr->character[key[i]] == nullptr)
+curr->character[key[i]] = new Trie();
+
+// go to next node
+curr = curr->character[key[i]];
+}
+
+// mark current node as leaf
+curr->isLeaf = true;
+}
+
+// Iterative function to search a key in Trie. It returns true
+// if the key is found in the Trie, else it returns false
+bool Trie::search(std::string key)
+{
+// return false if Trie is empty
+if (this == nullptr)
+return false;
+
+Trie* curr = this;
+for (int i = 0; i < key.length(); i++)
+{
+// go to next node
+curr = curr->character[key[i]];
+
+// if string is invalid (reached end of path in Trie)
+if (curr == nullptr)
+return false;
+}
+
+// if current node is a leaf and we have reached the
+// end of the string, return true
+return curr->isLeaf;
+}
+
+// returns true if given node has any children
+bool Trie::haveChildren(Trie const* curr)
+{
+for (int i = 0; i < CHAR_SIZE; i++)
+if (curr->character[i])
+return true;// child found
+
+return false;
+}
+
+// Recursive function to delete a key in the Trie
+bool Trie::deletion(Trie*& curr, std::string key)
+{
+// return if Trie is empty
+if (curr == nullptr)
+return false;
+
+// if we have not reached the end of the key
+if (key.length())
+{
+// recur for the node corresponding to next character in the key
+// and if it returns true, delete current node (if it is non-leaf)
+
+if (curr != nullptr &&
+curr->character[key[0]] != nullptr &&
+deletion(curr->character[key[0]], key.substr(1)) &&
+curr->isLeaf == false)
+{
+if (!haveChildren(curr))
+{
+delete curr;
+curr = nullptr;
+return true;
+}
+else {
+return false;
+}
+}
+}
+
+// if we have reached the end of the key
+if (key.length() == 0 && curr->isLeaf)
+{
+// if current node is a leaf node and don't have any children
+if (!haveChildren(curr))
+{
+// delete current node
+delete curr;
+curr = nullptr;
+
+// delete non-leaf parent nodes
+return true;
+}
+
+// if current node is a leaf node and have children
+else
+{
+// mark current node as non-leaf node (DON'T DELETE IT)
+curr->isLeaf = false;
+
+// don't delete its parent nodes
+return false;
+}
+}
+
+return false;
+}
+
+// C++ implementation of Trie Data Structure
+int main()
+{
+Trie* head = new Trie();
+
+head->insert("hello");
+std::cout << head->search("hello") << " "; // print 1
+
+head->insert("helloworld");
+std::cout << head->search("helloworld") << " "; // print 1
+
+std::cout << head->search("helll") << " "; // print 0 (Not found)
+
+head->insert("hell");
+std::cout << head->search("hell") << " "; // print 1
+
+head->insert("h");
+std::cout << head->search("h"); // print 1
+
+std::cout << std::endl;
+
+head->deletion(head, "hello");
+std::cout << head->search("hello") << " "; // print 0
+
+std::cout << head->search("helloworld") << " "; // print 1
+std::cout << head->search("hell"); // print 1
+
+std::cout << std::endl;
+
+head->deletion(head, "h");
+std::cout << head->search("h") << " "; // print 0
+std::cout << head->search("hell") << " "; // print 1
+std::cout << head->search("helloworld");// print 1
+
+std::cout << std::endl;
+
+head->deletion(head, "helloworld");
+std::cout << head->search("helloworld") << " "; // print 0
+std::cout << head->search("hell") << " "; // print 1
+
+head->deletion(head, "hell");
+std::cout << head->search("hell"); // print 0
+
+std::cout << std::endl;
+
+if (head == nullptr)
+std::cout << "Trie empty!!\n"; // Trie is empty now
+
+std::cout << head->search("hell"); // print 0
+
+return 0;
+}
+
+/*
+Output:
+
+1 1 0 1 1
+0 1 1
+0 1 1
+0 1 0
+Trie empty!!
+0
+
+*/