Implementați un Director telefonic
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#practiceLinkDiv { display: none !important; } Se oferă o listă de contacte care există într-un director telefonic. Sarcina este de a implementa o interogare de căutare pentru directorul telefonic. Interogarea de căutare pe un șir „ str ’ afișează toate contactele care au prefixele ca ‘ str ’. O proprietate specială a funcției de căutare este că, atunci când un utilizator caută un contact din lista de contacte, sugestiile (Contacte cu prefix ca șirul introdus astfel) sunt afișate după ce utilizatorul introduce fiecare caracter.
Nota: Contactele din listă constau numai din litere mici. Exemplu:
Input : contacts [] = {gforgeeks geeksquiz } Query String = gekk Output : Suggestions based on 'g' are geeksquiz gforgeeks Suggestions based on 'ge' are geeksquiz No Results Found for 'gek' No Results Found for 'gekk' Recomandat: Vă rugăm să rezolvați problema PRACTICA mai întâi înainte de a trece la soluție.
Phone Directory poate fi implementat eficient folosind Încearcă Structura datelor. Inserăm toate contactele în Trie. În general, interogarea de căutare pe un Trie este de a determina dacă șirul este prezent sau nu în trie, dar în acest caz ni se cere să găsim toate șirurile cu fiecare prefix de „str”. Acest lucru este echivalent cu a face a Parcurs DFS pe un grafic . Dintr-un nod Trie vizitați nodurile Trie adiacente și faceți acest lucru recursiv până când nu mai sunt adiacente. Această funcție recursivă va lua 2 argumente unul ca Trie Node care indică nodul Trie curent care este vizitat și altul ca șirul care stochează șirul găsit până acum cu prefixul „str”. Fiecare nod Trie stochează o variabilă booleană „isLast”, care este adevărată dacă nodul reprezintă sfârșitul unui contact (cuvânt).
// This function displays all words with given // prefix. 'node' represents last node when // path from root follows characters of 'prefix'. displayContacts (TreiNode node string prefix) If (node.isLast is true) display prefix // finding adjacent nodes for each character ‘i’ in lower case Alphabets if (node.child[i] != NULL) displayContacts(node.child[i] prefix+i)
Utilizatorul va introduce șirul caracter cu caracter și trebuie să afișăm sugestii cu prefixul format după fiecare caracter introdus. Deci, o abordare pentru a găsi prefixul care începe cu șirul format este de a verifica dacă prefixul există în Trie, dacă da, apoi apelați funcția displayContacts(). În această abordare, după fiecare caracter introdus, verificăm dacă șirul există în Trie. În loc să verificăm din nou și din nou, putem menține un pointer prevNode ' care indică TrieNode care corespunde ultimului caracter introdus de utilizator. Acum trebuie să verificăm nodul copil pentru „prevNode” când utilizatorul introduce un alt caracter pentru a verifica dacă acesta există în Trie. Dacă noul prefix nu este în Trie, atunci toate șirurile care sunt formate prin introducerea caracterelor după „prefix” nu pot fi găsite nici în Trie. Deci, întrerupem bucla care este folosită pentru a genera prefixe unul câte unul și tipărim „Niciun rezultat găsit” pentru toate caracterele rămase.
C++ // C++ Program to Implement a Phone // Directory Using Trie Data Structure #include using namespace std ; struct TrieNode { // Each Trie Node contains a Map 'child' // where each alphabet points to a Trie // Node. // We can also use a fixed size array of // size 256. unordered_map < char TrieNode *> child ; // 'isLast' is true if the node represents // end of a contact bool isLast ; // Default Constructor TrieNode () { // Initialize all the Trie nodes with NULL for ( char i = 'a' ; i <= 'z' ; i ++ ) child [ i ] = NULL ; isLast = false ; } }; // Making root NULL for ease so that it doesn't // have to be passed to all functions. TrieNode * root = NULL ; // Insert a Contact into the Trie void insert ( string s ) { int len = s . length (); // 'itr' is used to iterate the Trie Nodes TrieNode * itr = root ; for ( int i = 0 ; i < len ; i ++ ) { // Check if the s[i] is already present in // Trie TrieNode * nextNode = itr -> child [ s [ i ]]; if ( nextNode == NULL ) { // If not found then create a new TrieNode nextNode = new TrieNode (); // Insert into the Map itr -> child [ s [ i ]] = nextNode ; } // Move the iterator('itr') to point to next // Trie Node itr = nextNode ; // If its the last character of the string 's' // then mark 'isLast' as true if ( i == len - 1 ) itr -> isLast = true ; } } // This function simply displays all dictionary words // going through current node. String 'prefix' // represents string corresponding to the path from // root to curNode. void displayContactsUtil ( TrieNode * curNode string prefix ) { // Check if the string 'prefix' ends at this Node // If yes then display the string found so far if ( curNode -> isLast ) cout < < prefix < < endl ; // Find all the adjacent Nodes to the current // Node and then call the function recursively // This is similar to performing DFS on a graph for ( char i = 'a' ; i <= 'z' ; i ++ ) { TrieNode * nextNode = curNode -> child [ i ]; if ( nextNode != NULL ) displayContactsUtil ( nextNode prefix + ( char ) i ); } } // Display suggestions after every character enter by // the user for a given query string 'str' void displayContacts ( string str ) { TrieNode * prevNode = root ; string prefix = '' ; int len = str . length (); // Display the contact List for string formed // after entering every character int i ; for ( i = 0 ; i < len ; i ++ ) { // 'prefix' stores the string formed so far prefix += ( char ) str [ i ]; // Get the last character entered char lastChar = prefix [ i ]; // Find the Node corresponding to the last // character of 'prefix' which is pointed by // prevNode of the Trie TrieNode * curNode = prevNode -> child [ lastChar ]; // If nothing found then break the loop as // no more prefixes are going to be present. if ( curNode == NULL ) { cout < < ' n No Results Found for ' < < prefix < < ' n ' ; i ++ ; break ; } // If present in trie then display all // the contacts with given prefix. cout < < ' n Suggestions based on ' < < prefix < < 'are ' ; displayContactsUtil ( curNode prefix ); // Change prevNode for next prefix prevNode = curNode ; } // Once search fails for a prefix we print // 'Not Results Found' for all remaining // characters of current query string 'str'. for (; i < len ; i ++ ) { prefix += ( char ) str [ i ]; cout < < ' n No Results Found for ' < < prefix < < ' n ' ; } } // Insert all the Contacts into the Trie void insertIntoTrie ( string contacts [] int n ) { // Initialize root Node root = new TrieNode (); // Insert each contact into the trie for ( int i = 0 ; i < n ; i ++ ) insert ( contacts [ i ]); } // Driver program to test above functions int main () { // Contact list of the User string contacts [] = { 'gforgeeks' 'geeksquiz' }; // Size of the Contact List int n = sizeof ( contacts ) / sizeof ( string ); // Insert all the Contacts into Trie insertIntoTrie ( contacts n ); string query = 'gekk' ; // Note that the user will enter 'g' then 'e' so // first display all the strings with prefix as 'g' // and then all the strings with prefix as 'ge' displayContacts ( query ); return 0 ; }
Java // Java Program to Implement a Phone // Directory Using Trie Data Structure import java.util.* ; class TrieNode { // Each Trie Node contains a Map 'child' // where each alphabet points to a Trie // Node. HashMap < Character TrieNode > child ; // 'isLast' is true if the node represents // end of a contact boolean isLast ; // Default Constructor public TrieNode () { child = new HashMap < Character TrieNode > (); // Initialize all the Trie nodes with NULL for ( char i = 'a' ; i <= 'z' ; i ++ ) child . put ( i null ); isLast = false ; } } class Trie { TrieNode root ; // Insert all the Contacts into the Trie public void insertIntoTrie ( String contacts [] ) { root = new TrieNode (); int n = contacts . length ; for ( int i = 0 ; i < n ; i ++ ) { insert ( contacts [ i ] ); } } // Insert a Contact into the Trie public void insert ( String s ) { int len = s . length (); // 'itr' is used to iterate the Trie Nodes TrieNode itr = root ; for ( int i = 0 ; i < len ; i ++ ) { // Check if the s[i] is already present in // Trie TrieNode nextNode = itr . child . get ( s . charAt ( i )); if ( nextNode == null ) { // If not found then create a new TrieNode nextNode = new TrieNode (); // Insert into the HashMap itr . child . put ( s . charAt ( i ) nextNode ); } // Move the iterator('itr') to point to next // Trie Node itr = nextNode ; // If its the last character of the string 's' // then mark 'isLast' as true if ( i == len - 1 ) itr . isLast = true ; } } // This function simply displays all dictionary words // going through current node. String 'prefix' // represents string corresponding to the path from // root to curNode. public void displayContactsUtil ( TrieNode curNode String prefix ) { // Check if the string 'prefix' ends at this Node // If yes then display the string found so far if ( curNode . isLast ) System . out . println ( prefix ); // Find all the adjacent Nodes to the current // Node and then call the function recursively // This is similar to performing DFS on a graph for ( char i = 'a' ; i <= 'z' ; i ++ ) { TrieNode nextNode = curNode . child . get ( i ); if ( nextNode != null ) { displayContactsUtil ( nextNode prefix + i ); } } } // Display suggestions after every character enter by // the user for a given string 'str' void displayContacts ( String str ) { TrieNode prevNode = root ; // 'flag' denotes whether the string entered // so far is present in the Contact List String prefix = '' ; int len = str . length (); // Display the contact List for string formed // after entering every character int i ; for ( i = 0 ; i < len ; i ++ ) { // 'str' stores the string entered so far prefix += str . charAt ( i ); // Get the last character entered char lastChar = prefix . charAt ( i ); // Find the Node corresponding to the last // character of 'str' which is pointed by // prevNode of the Trie TrieNode curNode = prevNode . child . get ( lastChar ); // If nothing found then break the loop as // no more prefixes are going to be present. if ( curNode == null ) { System . out . println ( 'nNo Results Found for ' + prefix ); i ++ ; break ; } // If present in trie then display all // the contacts with given prefix. System . out . println ( 'nSuggestions based on ' + prefix + ' are ' ); displayContactsUtil ( curNode prefix ); // Change prevNode for next prefix prevNode = curNode ; } for ( ; i < len ; i ++ ) { prefix += str . charAt ( i ); System . out . println ( 'nNo Results Found for ' + prefix ); } } } // Driver code class Main { public static void main ( String args [] ) { Trie trie = new Trie (); String contacts [] = { 'gforgeeks' 'geeksquiz' }; trie . insertIntoTrie ( contacts ); String query = 'gekk' ; // Note that the user will enter 'g' then 'e' so // first display all the strings with prefix as 'g' // and then all the strings with prefix as 'ge' trie . displayContacts ( query ); } }
Python3 # Python Program to Implement a Phone # Directory Using Trie Data Structure class TrieNode : def __init__ ( self ): # Each Trie Node contains a Map 'child' # where each alphabet points to a Trie # Node. self . child = {} self . is_last = False # Making root NULL for ease so that it doesn't # have to be passed to all functions. root = TrieNode () # Insert a Contact into the Trie def insert ( string ): # 'itr' is used to iterate the Trie Nodes itr = root for char in string : # Check if the s[i] is already present in # Trie if char not in itr . child : # If not found then create a new TrieNode itr . child [ char ] = TrieNode () # Move the iterator('itr') to point to next # Trie Node itr = itr . child [ char ] # If its the last character of the string 's' # then mark 'isLast' as true itr . is_last = True # This function simply displays all dictionary words # going through current node. String 'prefix' # represents string corresponding to the path from # root to curNode. def display_contacts_util ( cur_node prefix ): # Check if the string 'prefix' ends at this Node # If yes then display the string found so far if cur_node . is_last : print ( prefix ) # Find all the adjacent Nodes to the current # Node and then call the function recursively # This is similar to performing DFS on a graph for i in range ( ord ( 'a' ) ord ( 'z' ) + 1 ): char = chr ( i ) next_node = cur_node . child . get ( char ) if next_node : display_contacts_util ( next_node prefix + char ) # Display suggestions after every character enter by # the user for a given query string 'str' def displayContacts ( string ): prev_node = root prefix = '' # Display the contact List for string formed # after entering every character for i char in enumerate ( string ): # 'prefix' stores the string formed so far prefix += char # Find the Node corresponding to the last # character of 'prefix' which is pointed by # prevNode of the Trie cur_node = prev_node . child . get ( char ) # If nothing found then break the loop as # no more prefixes are going to be present. if not cur_node : print ( f 'No Results Found for { prefix } n ' ) break # If present in trie then display all # the contacts with given prefix. print ( f 'Suggestions based on { prefix } are ' end = ' ' ) display_contacts_util ( cur_node prefix ) print () # Change prevNode for next prefix prev_node = cur_node # Once search fails for a prefix we print # 'Not Results Found' for all remaining # characters of current query string 'str'. for char in string [ i + 1 :]: prefix += char print ( f 'No Results Found for { prefix } n ' ) # Insert all the Contacts into the Trie def insertIntoTrie ( contacts ): # Insert each contact into the trie for contact in contacts : insert ( contact ) # Driver program to test above functions # Contact list of the User contacts = [ 'gforgeeks' 'geeksquiz' ] # Size of the Contact List n = len ( contacts ) # Insert all the Contacts into Trie insertIntoTrie ( contacts ) query = 'gekk' # Note that the user will enter 'g' then 'e' so # first display all the strings with prefix as 'g' # and then all the strings with prefix as 'ge' displayContacts ( query ) # This code is contributed by Aman Kumar
C# // C# Program to Implement a Phone // Directory Using Trie Data Structure using System ; using System.Collections.Generic ; class TrieNode { // Each Trie Node contains a Map 'child' // where each alphabet points to a Trie // Node. public Dictionary < char TrieNode > child ; // 'isLast' is true if the node represents // end of a contact public bool isLast ; // Default Constructor public TrieNode () { child = new Dictionary < char TrieNode > (); // Initialize all the Trie nodes with NULL for ( char i = 'a' ; i <= 'z' ; i ++ ) child . Add ( i null ); isLast = false ; } } class Trie { public TrieNode root ; // Insert all the Contacts into the Trie public void insertIntoTrie ( String [] contacts ) { root = new TrieNode (); int n = contacts . Length ; for ( int i = 0 ; i < n ; i ++ ) { insert ( contacts [ i ]); } } // Insert a Contact into the Trie public void insert ( String s ) { int len = s . Length ; // 'itr' is used to iterate the Trie Nodes TrieNode itr = root ; for ( int i = 0 ; i < len ; i ++ ) { // Check if the s[i] is already present in // Trie TrieNode nextNode = itr . child [ s [ i ]]; if ( nextNode == null ) { // If not found then create a new TrieNode nextNode = new TrieNode (); // Insert into the Dictionary if ( itr . child . ContainsKey ( s [ i ])) itr . child [ s [ i ]] = nextNode ; else itr . child . Add ( s [ i ] nextNode ); } // Move the iterator('itr') to point to next // Trie Node itr = nextNode ; // If its the last character of the string 's' // then mark 'isLast' as true if ( i == len - 1 ) itr . isLast = true ; } } // This function simply displays all dictionary words // going through current node. String 'prefix' // represents string corresponding to the path from // root to curNode. public void displayContactsUtil ( TrieNode curNode String prefix ) { // Check if the string 'prefix' ends at this Node // If yes then display the string found so far if ( curNode . isLast ) Console . WriteLine ( prefix ); // Find all the adjacent Nodes to the current // Node and then call the function recursively // This is similar to performing DFS on a graph for ( char i = 'a' ; i <= 'z' ; i ++ ) { TrieNode nextNode = curNode . child [ i ]; if ( nextNode != null ) { displayContactsUtil ( nextNode prefix + i ); } } } // Display suggestions after every character enter by // the user for a given string 'str' public void displayContacts ( String str ) { TrieNode prevNode = root ; // 'flag' denotes whether the string entered // so far is present in the Contact List String prefix = '' ; int len = str . Length ; // Display the contact List for string formed // after entering every character int i ; for ( i = 0 ; i < len ; i ++ ) { // 'str' stores the string entered so far prefix += str [ i ]; // Get the last character entered char lastChar = prefix [ i ]; // Find the Node corresponding to the last // character of 'str' which is pointed by // prevNode of the Trie TrieNode curNode = prevNode . child [ lastChar ]; // If nothing found then break the loop as // no more prefixes are going to be present. if ( curNode == null ) { Console . WriteLine ( 'nNo Results Found for ' + prefix ); i ++ ; break ; } // If present in trie then display all // the contacts with given prefix. Console . WriteLine ( 'nSuggestions based on ' + prefix + ' are ' ); displayContactsUtil ( curNode prefix ); // Change prevNode for next prefix prevNode = curNode ; } for ( ; i < len ; i ++ ) { prefix += str [ i ]; Console . WriteLine ( 'nNo Results Found for ' + prefix ); } } } // Driver code public class GFG { public static void Main ( String [] args ) { Trie trie = new Trie (); String [] contacts = { 'gforgeeks' 'geeksquiz' }; trie . insertIntoTrie ( contacts ); String query = 'gekk' ; // Note that the user will enter 'g' then 'e' so // first display all the strings with prefix as 'g' // and then all the strings with prefix as 'ge' trie . displayContacts ( query ); } } // This code is contributed by PrinciRaj1992
JavaScript < script > // Javascript Program to Implement a Phone // Directory Using Trie Data Structure class TrieNode { constructor () { // Each Trie Node contains a Map 'child' // where each alphabet points to a Trie // Node. // We can also use a fixed size array of // size 256. this . child = {}; // 'isLast' is true if the node represents // end of a contact this . isLast = false ; } } // Making root NULL for ease so that it doesn't // have to be passed to all functions. let root = null ; // Insert a Contact into the Trie function insert ( s ) { const len = s . length ; // 'itr' is used to iterate the Trie Nodes let itr = root ; for ( let i = 0 ; i < len ; i ++ ) { // Check if the s[i] is already present in // Trie const char = s [ i ]; let nextNode = itr . child [ char ]; if ( nextNode === undefined ) { // If not found then create a new TrieNode nextNode = new TrieNode (); // Insert into the Map itr . child [ char ] = nextNode ; } // Move the iterator('itr') to point to next // Trie Node itr = nextNode ; // If its the last character of the string 's' // then mark 'isLast' as true if ( i === len - 1 ) { itr . isLast = true ; } } } // This function simply displays all dictionary words // going through current node. String 'prefix' // represents string corresponding to the path from // root to curNode. function displayContactsUtil ( curNode prefix ) { // Check if the string 'prefix' ends at this Node // If yes then display the string found so far if ( curNode . isLast ) { document . write ( prefix + '
' ); } // Find all the adjacent Nodes to the current // Node and then call the function recursively // This is similar to performing DFS on a graph for ( let i = 97 ; i <= 122 ; i ++ ) { const char = String . fromCharCode ( i ); const nextNode = curNode . child [ char ]; if ( nextNode !== undefined ) { displayContactsUtil ( nextNode prefix + char ); } } } // Display suggestions after every character enter by // the user for a given query string 'str' function displayContacts ( str ) { let prevNode = root ; let prefix = '' ; const len = str . length ; // Display the contact List for string formed // after entering every character let i ; for ( i = 0 ; i < len ; i ++ ) { // 'prefix' stores the string formed so far prefix += str [ i ]; // Get the last character entered const lastChar = prefix [ i ]; // Find the Node corresponding to the last // character of 'prefix' which is pointed by // prevNode of the Trie const curNode = prevNode . child [ lastChar ]; // If nothing found then break the loop as // no more prefixes are going to be present. if ( curNode === undefined ) { document . write ( `No Results Found for ${ prefix } ` + '
' ); i ++ ; break ; } // If present in trie then display all // the contacts with given prefix. document . write ( `Suggestions based on ${ prefix } are ` ); displayContactsUtil ( curNode prefix ); document . write ( '
' ); // Change prevNode for next prefix prevNode = curNode ; } document . write ( '
' ); // Once search fails for a prefix we print // 'Not Results Found' for all remaining // characters of current query string 'str'. for (; i < len ; i ++ ) { prefix += str [ i ]; document . write ( 'No Results Found for ' + prefix + '
' ); } } // Insert all the Contacts into the Trie function insertIntoTrie ( contacts ) { // Initialize root Node root = new TrieNode (); const n = contacts . length ; // Insert each contact into the trie for ( let i = 0 ; i < n ; i ++ ) { insert ( contacts [ i ]); } } // Driver program to test above functions // Contact list of the User const contacts = [ 'gforgeeks' 'geeksquiz' ]; //Insert all the Contacts into Trie insertIntoTrie ( contacts ); const query = 'gekk' ; // Note that the user will enter 'g' then 'e' so // first display all the strings with prefix as 'g' // and then all the strings with prefix as 'ge' displayContacts ( query ); // This code is contributed by Utkarsh Kumar. < /script>
Ieșire
Suggestions based on gare geeksquiz gforgeeks Suggestions based on geare geeksquiz No Results Found for gek No Results Found for gekk
Complexitatea timpului: O(n*m) unde n este numărul de contacte și m este lungimea maximă a unui șir de contacte.
Spațiu auxiliar: O(n*m)
