Create main.cpp

Author: JawadSher

21 - Trie Data Structure Problems/04 - Phone Directory/main.cpp

@@ -0,0 +1,100 @@
+class TrieNode {
+    public:
+        char data;
+        TrieNode* children[26];
+        bool isTerminal;
+        
+        TrieNode(char data){
+            this -> data = data;
+            for(int i = 0; i < 26; i++) children[i] = NULL;
+            isTerminal = false;
+        }
+};
+
+class Trie {
+    public:
+        TrieNode* root;
+        
+        Trie(char ch) {
+            root = new TrieNode(ch);
+        }
+        
+        void insertUtil(TrieNode* root, string word, int index){
+            if(index == word.size()){
+                root -> isTerminal = true;
+                return;
+            }
+            
+            int charIndex = word[index] - 'a';
+            if(root -> children[charIndex] == NULL) root -> children[charIndex] = new TrieNode(word[index]);
+            
+            insertUtil(root -> children[charIndex], word, index+1);
+        }
+        
+        void insertWord(string word){
+            insertUtil(root, word, 0);
+        }
+        
+        
+        
+        void printSuggestions(TrieNode* curr, vector<string>& temp, string prefix){
+            if(curr -> isTerminal){
+                temp.push_back(prefix);
+            }
+            
+            for(char ch = 'a'; ch <= 'z'; ch++){
+                TrieNode* next = curr -> children[ch - 'a'];
+                if(next != NULL){
+                    prefix.push_back(ch);
+                    printSuggestions(next, temp, prefix);
+                    prefix.pop_back();
+                }
+            }
+        }
+        
+        vector<vector<string>> getSuggestions(string str){
+            TrieNode* prev = root;
+            vector<vector<string>> output;
+            
+            string prefix = "";
+            
+            for(int i = 0; i < str.length(); i++){
+                char lastChar = str[i];
+                prefix.push_back(lastChar);
+                
+                TrieNode* curr = prev -> children[lastChar - 'a'];
+                if(curr == NULL) {
+                    for(int j = i; j < str.length(); j++) output.push_back({"0"});
+                    break;
+                }
+                
+                vector<string> temp;
+                printSuggestions(curr, temp, prefix);
+                
+                if(temp.empty()) output.push_back({"0"});
+                else{
+                    sort(temp.begin(), temp.end());
+                    output.push_back(temp);
+                }
+                
+                prev = curr;
+            }
+            
+            return output;
+        }
+        
+};
+
+class Solution {
+public:
+    vector<vector<string>> displayContacts(int n, string contact[], string s) {
+        Trie* t = new Trie('\0');
+        
+        for(int i = 0; i < n; i++){
+            string str = contact[i];
+            t -> insertWord(str);
+        }
+        
+        return t -> getSuggestions(s);
+    }
+};