Trie es una estructura de datos de recuperación de información eficiente. Con Trie, las complejidades de búsqueda se pueden llevar a un límite óptimo (longitud de clave).
La tarea es buscar una string en un Trie usando recursividad.
Ejemplos:
root
/ \
t a
| |
h n
| | \
e s y
/ | |
i r w
| | |
r e e
|
r
Input : str = "anywhere"
Output : not found
Input : str = "answer"
Output : found
Enfoque:
buscar una clave es similar a la operación de inserción , sin embargo, solo comparamos los caracteres y nos movemos hacia abajo. La búsqueda puede terminar debido al final de una string o falta de clave en el trie. En el primer caso, si el campo endOfWord del último Node es verdadero, entonces la clave existe en el trie. En el segundo caso, la búsqueda termina sin examinar todos los caracteres de la clave, ya que la clave no está presente en el trie.
A continuación se muestra la implementación del enfoque anterior:
C++
// CPP program to search in a trie
#include <bits/stdc++.h>
using namespace std;
#define CHILDREN 26
#define MAX 100
// Trie node
struct trie {
trie* child[CHILDREN];
// endOfWord is true if the node represents
// end of a word
bool endOfWord;
};
// Function will return the new node(initialized to NULLs)
trie* createNode()
{
trie* temp = new trie();
temp->endOfWord = false;
for (int i = 0; i < CHILDREN; i++) {
// initially assign null to the all child
temp->child[i] = NULL;
}
return temp;
}
/*function will insert the string in a trie recursively*/
void insertRecursively(trie* itr, string str, int i)
{
if (i < str.length()) {
int index = str[i] - 'a';
if (itr->child[index] == NULL) {
// Insert a new node
itr->child[index] = createNode();
}
// Recursive call for insertion of a string
insertRecursively(itr->child[index], str, i + 1);
}
else {
// Make the endOfWord true which represents
// the end of string
itr->endOfWord = true;
}
}
// Function call to insert a string
void insert(trie* itr, string str)
{
// Function call with necessary arguments
insertRecursively(itr, str, 0);
}
// Function to search the string in a trie recursively
bool searchRecursively(trie* itr, char str[], int i,
int len)
{
// When a string or any character
// of a string is not found
if (itr == NULL)
return false;
// Condition of finding string successfully
if (itr->endOfWord == true && i == len - 1) {
// Return true when endOfWord
// of last node containes true
return true;
}
int index = str[i] - 'a';
// Recursive call and return
// value of function call stack
return searchRecursively(itr->child[index],
str, i + 1, len);
}
// Function call to search the string
void search(trie* root, string str)
{
char arr[str.length() + 1];
strcpy(arr, str.c_str());
// If string found
if (searchRecursively(root, arr, 0, str.length() + 1))
cout << "found" << endl;
else {
cout << "not found" << endl;
}
}
// Driver code
int main()
{
trie* root = createNode();
// Function call to insert the string
insert(root, "their");
insert(root, "there");
insert(root, "answer");
insert(root, "any");
// Function call to search the string
search(root, "anywhere");
search(root, "answer");
return 0;
}
Java
// Java program to search in a trie
import java.util.*;
public class Main
{
static int CHILDREN = 26;
// Trie node
static class trie {
public boolean endOfWord;
public trie[] child;
public trie()
{
endOfWord = false;
// endOfWord is true if the node represents
// end of a word
child = new trie[CHILDREN];
}
}
// Function will return the new node(initialized to NULLs)
static trie createNode()
{
trie temp = new trie();
temp.endOfWord = false;
for (int i = 0; i < CHILDREN; i++)
{
// Initialise all child to the null, initially
temp.child[i] = null;
}
// Return newly created node
return temp;
}
// Function will insert the string in a trie recursively
static void insertRecursively(trie itr, String str, int i)
{
if (i < str.length()) {
int index = str.charAt(i) - 'a';
if (itr.child[index] == null)
{
// Assigning a newly created node
itr.child[index] = createNode();
}
// Recursive call for insertion
// of a string in a trie
insertRecursively(itr.child[index], str, i + 1);
}
else
{
// Make the endOfWord true which represents
// the end of string
itr.endOfWord = true;
}
}
// Function call to insert a string
static void insert(trie itr, String str)
{
// Function call with necessary arguments
insertRecursively(itr, str, 0);
}
// Function to search the string in a trie recursively
static boolean searchRecursively(trie itr, char[] str, int i, int len)
{
// When a string or any character
// of a string is not found
if (itr == null)
return false;
// Condition of finding string successfully
if (itr.endOfWord == true && i == len - 1)
{
// Return true when endOfWord
// of last node containes true
return true;
}
int index = str[i] - 'a';
// Recursive call and return
// value of function call stack
return searchRecursively(itr.child[index], str, i + 1, len);
}
// Function call to search the string
static void search(trie root, String str)
{
char[] arr = new char[str.length() + 1];
for(int i = 0; i < str.length(); i++)
{
arr[i] = str.charAt(i);
}
// If string found
if (searchRecursively(root, arr, 0, str.length() + 1))
System.out.println("found");
else {
System.out.println("not found");
}
}
public static void main(String[] args) {
trie root = createNode();
// Function call to insert the string
insert(root, "their");
insert(root, "there");
insert(root, "answer");
insert(root, "any");
// Function call to search the string
search(root, "anywhere");
search(root, "answer");
}
}
// This code is contributed by suresh07.
Python3
# Python3 program to traverse in bottom up manner
CHILDREN = 26
MAX = 100
# Trie node
class trie:
def __init__(self):
self.child = [None for i in range(CHILDREN)]
# endOfWord is true if the node represents
# end of a word
self.endOfWord = False
# Function will return the new node(initialized to NULLs)
def createNode():
temp = trie()
return temp
# Function will insert the string in a trie recursively
def insertRecursively(itr, str, i):
if(i < len(str)):
index = ord(str[i]) - ord('a')
if(itr.child[index] == None ):
# Insert a new node
itr.child[index] = createNode();
# Recursive call for insertion of string
insertRecursively(itr.child[index], str, i + 1);
else:
# Make the endOfWord true which represents
# the end of string
itr.endOfWord = True;
# Function call to insert a string
def insert(itr, str):
# Function call with necessary arguments
insertRecursively(itr, str, 0);
# Function to search the string in a trie recursively
def searchRecursively(itr ,str, i, len):
# When a string or any character
# of a string is not found
if (itr == None):
return False
# Condition of finding string successfully
if (itr.endOfWord == True and i == len - 1):
# Return true when endOfWord
# of last node containes true
return True
index = ord(str[i]) - ord('a')
# Recursive call and return
# value of function call stack
return searchRecursively(itr.child[index], str, i + 1, len)
# Function call to search the string
def search(root, str):
arr = ['' for i in range(len(str) + 1)]
arr = str
# If string found
if (searchRecursively(root, arr, 0, len(str) + 1)):
print("found")
else:
print("not found")
# Driver code
if __name__=='__main__':
root = createNode();
# Function call to insert the string
insert(root, "their");
insert(root, "there");
insert(root, "answer");
insert(root, "any");
# Function call to search the string
search(root, "anywhere")
search(root, "answer")
# This code is contributed by rutvik_56
C#
// C# program to search in a trie
using System;
class GFG {
static int CHILDREN = 26;
// Trie node
class trie {
public bool endOfWord;
public trie[] child;
public trie()
{
endOfWord = false;
// endOfWord is true if the node represents
// end of a word
child = new trie[CHILDREN];
}
}
// Function will return the new node(initialized to NULLs)
static trie createNode()
{
trie temp = new trie();
temp.endOfWord = false;
for (int i = 0; i < CHILDREN; i++) {
// Initialise all child to the null, initially
temp.child[i] = null;
}
// Return newly created node
return temp;
}
// Function will insert the string in a trie recursively
static void insertRecursively(trie itr, string str, int i)
{
if (i < str.Length) {
int index = str[i] - 'a';
if (itr.child[index] == null) {
// Assigning a newly created node
itr.child[index] = createNode();
}
// Recursive call for insertion
// of a string in a trie
insertRecursively(itr.child[index], str, i + 1);
}
else {
// Make the endOfWord true which represents
// the end of string
itr.endOfWord = true;
}
}
// Function call to insert a string
static void insert(trie itr, string str)
{
// Function call with necessary arguments
insertRecursively(itr, str, 0);
}
// Function to search the string in a trie recursively
static bool searchRecursively(trie itr, char[] str, int i, int len)
{
// When a string or any character
// of a string is not found
if (itr == null)
return false;
// Condition of finding string successfully
if (itr.endOfWord == true && i == len - 1) {
// Return true when endOfWord
// of last node containes true
return true;
}
int index = str[i] - 'a';
// Recursive call and return
// value of function call stack
return searchRecursively(itr.child[index], str, i + 1, len);
}
// Function call to search the string
static void search(trie root, string str)
{
char[] arr = new char[str.Length + 1];
for(int i = 0; i < str.Length; i++)
{
arr[i] = str[i];
}
// If string found
if (searchRecursively(root, arr, 0, str.Length + 1))
Console.WriteLine("found");
else {
Console.WriteLine("not found");
}
}
static void Main() {
trie root = createNode();
// Function call to insert the string
insert(root, "their");
insert(root, "there");
insert(root, "answer");
insert(root, "any");
// Function call to search the string
search(root, "anywhere");
search(root, "answer");
}
}
// This code is contributed by mukesh07.
Javascript
<script>
// Javascript program to search in a trie
let CHILDREN = 26;
// Trie node
class trie
{
constructor() {
this.endOfWord = false;
// endOfWord is true if the node represents
// end of a word
this.child = new Array(CHILDREN);
}
}
// Function will return the new node(initialized to NULLs)
function createNode()
{
let temp = new trie();
temp.endOfWord = false;
for (let i = 0; i < CHILDREN; i++) {
// Initialise all child to the null, initially
temp.child[i] = null;
}
// Return newly created node
return temp;
}
// Function will insert the string in a trie recursively
function insertRecursively(itr, str, i)
{
if (i < str.length) {
let index = str[i] - 'a';
if (itr.child[index] == null) {
// Assigning a newly created node
itr.child[index] = createNode();
}
// Recursive call for insertion
// of a string in a trie
insertRecursively(itr.child[index], str, i + 1);
}
else {
// Make the endOfWord true which represents
// the end of string
itr.endOfWord = true;
}
}
// Function call to insert a string
function insert(itr, str)
{
// Function call with necessary arguments
insertRecursively(itr, str, 0);
}
// Function to search the string in a trie recursively
function searchRecursively(itr, str, i, len)
{
// When a string or any character
// of a string is not found
if (itr == null)
return false;
// Condition of finding string successfully
if (itr.endOfWord == true && i == len - 1) {
// Return true when endOfWord
// of last node containes true
return true;
}
let index = str[i] - 'a';
// Recursive call and return
// value of function call stack
return searchRecursively(itr.child[index], str, i + 1, len);
}
// Function call to search the string
function search(root, str)
{
let arr = new Array(str.length + 1);
for(let i = 0; i < str.length; i++)
{
arr[i] = str[i];
}
// If string found
if (searchRecursively(root, arr, 0, str.length + 1))
document.write("found" + "</br>");
else {
document.write("not found" + "</br>");
}
}
let root = createNode();
// Function call to insert the string
insert(root, "their");
insert(root, "there");
insert(root, "answer");
insert(root, "any");
// Function call to search the string
search(root, "anywhere");
search(root, "answer");
// This code is contributed by divyeshrabadiya07.
</script>
Producción:
not found found
Publicación traducida automáticamente
Artículo escrito por MohammadMudassir y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA