Create Implement Trie- II

Implement Trie- II

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+Implement Trie – II
+Problem Statement:  Implement a data structure ”TRIE” from scratch. Complete some functions.
+
+1) Trie(): Initialize the object of this “TRIE” data structure.
+
+2) insert(“WORD”): Insert the string “WORD”  into this “TRIE” data structure.
+
+3) countWordsEqualTo(“WORD”): Return how many times this “WORD” is present in this “TRIE”.
+
+4) countWordsStartingWith(“PREFIX”): Return how many words are there in this “TRIE” that have the string “PREFIX” as a prefix.
+
+5) erase(“WORD”): Delete this string “WORD” from the “TRIE”.
+
+Note:
+
+1. If erase(“WORD”) function is called then it is guaranteed that the “WORD” is present in the “TRIE”.
+
+2. If you are going to use variables with dynamic memory allocation then you need to release the memory associated with them at the end of your solution.
+
+Example:
+Input: 
+1
+6
+insert samsung
+insert samsung
+insert  vivo
+erase vivo
+countWordsEqualTo samsung
+countWordsStartingWith vi
+Output: 
+2
+0
+
+Explanation: 
+
+Insert “samsung”: we are going to insert the word “samsung” into the “TRIE”.
+Insert “samsung”: we are going to insert the word “samsung” again into the “TRIE”.
+Insert “vivo”: we are going to insert the word “vivo” into the “TRIE”.
+Erase “vivo”: we are going to delete the word “vivo” from the “TRIE”.
+countWordsEqualTo “samsung”: There are two instances of “samsung” is present in “TRIE”.
+countWordsStartWith “vi”:There is not a single word in the “TRIE” that starts from the prefix “vi”.
+
+Solution
+#include <bits/stdc++.h>
+
+using namespace std;
+struct Node {
+  Node * links[26];
+  int cntEndWith = 0;
+  int cntPrefix = 0;
+
+  bool containsKey(char ch) {
+    return (links[ch - 'a'] != NULL);
+  }
+  Node * get(char ch) {
+    return links[ch - 'a'];
+  }
+  void put(char ch, Node * node) {
+    links[ch - 'a'] = node;
+  }
+  void increaseEnd() {
+    cntEndWith++;
+  }
+  void increasePrefix() {
+    cntPrefix++;
+  }
+  void deleteEnd() {
+    cntEndWith--;
+  }
+  void reducePrefix() {
+    cntPrefix--;
+  }
+  int getEnd() {
+    return cntEndWith;
+  }
+  int getPrefix() {
+    return cntPrefix;
+  }
+};
+class Trie {
+  private:
+    Node * root;
+
+  public:
+    /** Initialize your data structure here. */
+    Trie() {
+      root = new Node();
+    }
+
+  /** Inserts a word into the trie. */
+  void insert(string word) {
+    Node * node = root;
+    for (int i = 0; i < word.length(); i++) {
+      if (!node -> containsKey(word[i])) {
+        node -> put(word[i], new Node());
+      }
+      node = node -> get(word[i]);
+      node -> increasePrefix();
+    }
+    node -> increaseEnd();
+  }
+
+ int countWordsEqualTo(string &word)
+    {
+        Node *node = root;
+        for (int i = 0; i < word.length(); i++)
+        {
+            if (node->containsKey(word[i]))
+            {
+                node = node->get(word[i]);
+            }
+            else
+            {
+                return 0;
+            }
+        }
+        return node->getEnd();
+    }
+
+
+  int countWordsStartingWith(string & word) {
+    Node * node = root;
+    for (int i = 0; i < word.length(); i++) {
+      if (node -> containsKey(word[i])) {
+        node = node -> get(word[i]);
+      } else {
+        return 0;
+      }
+    }
+    return node -> getPrefix();
+  }
+
+  void erase(string & word) {
+    Node * node = root;
+    for (int i = 0; i < word.length(); i++) {
+      if (node -> containsKey(word[i])) {
+        node = node -> get(word[i]);
+        node -> reducePrefix();
+      } else {
+        return;
+      }
+    }
+    node -> deleteEnd();
+  }
+};
+
+int main() {
+  Trie T;
+  T.insert("apple");
+  T.insert("apple");
+  T.insert("apps");
+  T.insert("apps");
+  string word1 = "apps";
+  cout<<"Count Words Equal to "<< word1<<" "<<T.countWordsEqualTo(word1)<<endl;
+  string word2 = "abc";
+  cout<<"Count Words Equal to "<< word2<<" "<<T.countWordsEqualTo(word2)<<endl;
+  string word3 = "ap";
+  cout<<"Count Words Starting With "<<word3<<" "<<T.countWordsStartingWith(word3)
+  <<endl;
+  string word4 = "appl";
+  cout<<"Count Words Starting With "<< word4<<" "<<T.countWordsStartingWith(word4)
+  <<endl;
+  T.erase(word1);
+  cout<<"Count Words equal to "<< word1<<" "<<T.countWordsEqualTo(word1)<<endl;
+  return 0;
+}