Create Trie.cpp

data-structures/Trie.cpp

@@ -0,0 +1,79 @@
+#include <bits/stdc++.h> 
+using namespace std; 
+const int SIZE = 26; 
+
+struct MyNode{ 
+    struct MyNode *children[SIZE];
+    bool isEndOfWord; 
+}; 
+
+// Returns new trie node
+struct MyNode *getNode(void) 
+{ 
+    struct MyNode *pNode =  new MyNode; 
+
+    pNode->isEndOfWord = false; 
+
+    for (int i = 0; i < 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 MyNode *root, string key) 
+{ 
+    struct MyNode *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 MyNode *root, string key) 
+{ 
+    struct MyNode *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 Programme to check above functions
+int main() 
+{ 
+    // For input keys use only lower case 
+    string keys[] = {"the", "a", "there", 
+                    "answer", "any", "by", 
+                     "bye", "their" }; 
+    int n = sizeof(keys)/sizeof(keys[0]); 
+
+    struct MyNode *root = getNode(); 
+
+    // Build trie 
+    for (int i = 0; i < n; i++) 
+        insert(root, keys[i]); 
+
+    // Search for different keys to check is it present in our dictonary or not..?? 
+    search(root, "the")? cout << "Yes\n" : cout << "No\n"; 
+    search(root, "these")? cout << "Yes\n" : cout << "No\n"; 
+    return 0; 
+}