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Author: starwiz-7

Day14.cpp

@@ -0,0 +1,107 @@
+/*
+    Author: Aryan Yadav
+    Implement Trie (Prefix Tree)
+
+    Complexity: O(n)
+    Algorithm: NA
+    Difficulty: Hard
+    Data Structure: Trie
+*/
+
+class TrieNode
+{
+public:
+    // Initialize your data structure here.
+    TrieNode()
+    {
+        count = 0;
+        for (int i = 0; i < 26; ++i)
+        {
+            next[i] = NULL;
+        }
+    }
+
+    int count;
+    TrieNode *next[26];
+};
+
+class Trie
+{
+public:
+    Trie()
+    {
+        root = new TrieNode();
+    }
+
+    ~Trie()
+    {
+        this->deleteNodes(root);
+    }
+
+    // Inserts a word into the trie.
+    void insert(string key)
+    {
+        TrieNode *cur = this->root;
+        for (size_t i = 0; i < key.size(); ++i)
+        {
+            if (cur->next[key[i] - 'a'] == NULL)
+            {
+                cur->next[key[i] - 'a'] = new TrieNode();
+            }
+            cur = cur->next[key[i] - 'a'];
+        }
+        ++cur->count;
+    }
+
+    // Returns if the word is in the trie.
+    bool search(string key)
+    {
+        return getTargetCount(key) > 0;
+    }
+
+    // Returns if there is any word in the trie
+    // that starts with the given prefix.
+    bool startsWith(string prefix)
+    {
+        return this->getTargetCount(prefix) != -1;
+    }
+
+    void deleteNodes(TrieNode *node)
+    {
+        if (node == NULL)
+        {
+            return;
+        }
+
+        for (size_t i = 0; i < 26; ++i)
+        {
+            this->deleteNodes(node->next[i]);
+        }
+
+        delete node;
+    }
+
+private:
+    int getTargetCount(string key)
+    {
+        TrieNode *cur = this->root;
+        for (size_t i = 0; i < key.size(); ++i)
+        {
+            if (cur->next[key[i] - 'a'] == NULL)
+            {
+                return -1;
+            }
+            cur = cur->next[key[i] - 'a'];
+        }
+        return cur->count;
+    }
+    TrieNode *root;
+};
+
+/**
+ * Your Trie object will be instantiated and called as such:
+ * Trie* obj = new Trie();
+ * obj->insert(word);
+ * bool param_2 = obj->search(word);
+ * bool param_3 = obj->startsWith(prefix);
+ */