Added code for Trie Data Structure (insertion + find)

Data-Structures/Trie.cpp

@@ -0,0 +1,91 @@
+// C++ implementation of search and insert 
+// operations on Trie 
+#include <bits/stdc++.h> 
+using namespace std; 
+
+const int ALPHABET_SIZE = 26; 
+
+// trie node 
+struct TrieNode 
+{ 
+	struct TrieNode *children[ALPHABET_SIZE]; 
+
+	// isEndOfWord is true if the node represents 
+	// end of a word 
+	bool isEndOfWord; 
+}; 
+
+// Returns new trie node (initialized to NULLs) 
+struct TrieNode *getNode(void) 
+{ 
+	struct TrieNode *pNode = new TrieNode; 
+
+	pNode->isEndOfWord = false; 
+
+	for (int i = 0; i < ALPHABET_SIZE; i++) 
+		pNode->children[i] = NULL; 
+
+	return pNode; 
+} 
+
+// If not present, inserts key into trie 
+// If the key is prefix of trie node, just 
+// marks leaf node 
+void insert(struct TrieNode *root, string key) 
+{ 
+	struct TrieNode *pCrawl = root; 
+
+	for (int i = 0; i < key.length(); i++) 
+	{ 
+		int index = key[i] - 'a'; 
+		if (!pCrawl->children[index]) 
+			pCrawl->children[index] = getNode(); 
+
+		pCrawl = pCrawl->children[index]; 
+	} 
+
+	// mark last node as leaf 
+	pCrawl->isEndOfWord = true; 
+} 
+
+// Returns true if key presents in trie, else 
+// false 
+bool search(struct TrieNode *root, string key) 
+{ 
+	struct TrieNode *pCrawl = root; 
+
+	for (int i = 0; i < key.length(); i++) 
+	{ 
+		int index = key[i] - 'a'; 
+		if (!pCrawl->children[index]) 
+			return false; 
+
+		pCrawl = pCrawl->children[index]; 
+	} 
+
+	return (pCrawl != NULL && pCrawl->isEndOfWord); 
+} 
+
+// Driver 
+int main() 
+{ 
+	// Input keys (use only 'a' through 'z' 
+	// and lower case) 
+	string keys[] = {"the", "a", "there", 
+					"answer", "any", "by", 
+					"bye", "their" }; 
+	int n = sizeof(keys)/sizeof(keys[0]); 
+
+	struct TrieNode *root = getNode(); 
+
+	// Construct trie 
+	for (int i = 0; i < n; i++) 
+		insert(root, keys[i]); 
+
+	// Search for different keys 
+	search(root, "the")? cout << "Yes\n" : 
+						cout << "No\n"; 
+	search(root, "these")? cout << "Yes\n" : 
+						cout << "No\n"; 
+	return 0; 
+}