Escriba una función GetNth() que tome una lista enlazada y un índice entero y devuelva el valor de datos almacenado en el Node en esa posición de índice.
Ejemplo:
Input: 1->10->30->14, index = 2 Output: 30 The node at index 2 is 30
Algoritmo:
1. Initialize count = 0
2. Loop through the link list
a. if the count is equal to the passed index then return the current
node
b. Increment count
c. change current to point to next of the current.
Implementación:
C++
// C++ program to find n'th
// node in linked list
#include <assert.h>
#include <bits/stdc++.h>
using namespace std;
// Link list node
class Node {
public:
int data;
Node* next;
};
/* Given a reference (pointer to
pointer) to the head of a list
and an int, push a new node on
the front of the list. */
void push(Node** head_ref, int new_data)
{
// allocate node
Node* new_node = new Node();
// put in the data
new_node->data = new_data;
// link the old list
// off the new node
new_node->next = (*head_ref);
// move the head to point
// to the new node
(*head_ref) = new_node;
}
// Takes head pointer of
// the linked list and index
// as arguments and return
// data at index
int GetNth(Node* head, int index)
{
Node* current = head;
// the index of the
// node we're currently
// looking at
int count = 0;
while (current != NULL) {
if (count == index)
return (current->data);
count++;
current = current->next;
}
/* if we get to this line,
the caller was asking
for a non-existent element
so we assert fail */
assert(0);
}
// Driver Code
int main()
{
// Start with the
// empty list
Node* head = NULL;
// Use push() to construct
// below list
// 1->12->1->4->1
push(&head, 1);
push(&head, 4);
push(&head, 1);
push(&head, 12);
push(&head, 1);
// Check the count
// function
cout << "Element at index 3 is " << GetNth(head, 3);
return 0;
}
// This code is contributed by rathbhupendra
C
// C program to find n'th
// node in linked list
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
// Link list node
struct Node {
int data;
struct Node* next;
};
/* Given a reference (pointer to
pointer) to the head of a list
and an int, push a new node on
the front of the list. */
void push(struct Node** head_ref, int new_data)
{
// allocate node
struct Node* new_node
= (struct Node*)malloc(sizeof(struct Node));
// put in the data
new_node->data = new_data;
// link the old list
// off the new node
new_node->next = (*head_ref);
// move the head to point
// to the new node
(*head_ref) = new_node;
}
// Takes head pointer of
// the linked list and index
// as arguments and return
// data at index
int GetNth(struct Node* head, int index)
{
struct Node* current = head;
// the index of the
// node we're currently
// looking at
int count = 0;
while (current != NULL) {
if (count == index)
return (current->data);
count++;
current = current->next;
}
/* if we get to this line,
the caller was asking
for a non-existent element
so we assert fail */
assert(0);
}
// Driver Code
int main()
{
// Start with the
// empty list
struct Node* head = NULL;
// Use push() to construct
// below list
// 1->12->1->4->1
push(&head, 1);
push(&head, 4);
push(&head, 1);
push(&head, 12);
push(&head, 1);
// Check the count
// function
printf("Element at index 3 is %d", GetNth(head, 3));
getchar();
}
Java
// Java program to find n'th node in linked list
class Node {
int data;
Node next;
Node(int d)
{
data = d;
next = null;
}
}
class LinkedList {
Node head; // the head of list
/* Takes index as argument and return data at index*/
public int GetNth(int index)
{
Node current = head;
int count = 0; /* index of Node we are
currently looking at */
while (current != null)
{
if (count == index)
return current.data;
count++;
current = current.next;
}
/* if we get to this line, the caller was asking
for a non-existent element so we assert fail */
assert (false);
return 0;
}
/* Given a reference to the head of a list and an int,
inserts a new Node on the front of the list. */
public void push(int new_data)
{
/* 1. alloc the Node and put data*/
Node new_Node = new Node(new_data);
/* 2. Make next of new Node as head */
new_Node.next = head;
/* 3. Move the head to point to new Node */
head = new_Node;
}
/* Driver code*/
public static void main(String[] args)
{
/* Start with empty list */
LinkedList llist = new LinkedList();
/* Use push() to construct below list
1->12->1->4->1 */
llist.push(1);
llist.push(4);
llist.push(1);
llist.push(12);
llist.push(1);
/* Check the count function */
System.out.println("Element at index 3 is "
+ llist.GetNth(3));
}
}
Python3
# A complete working Python program to find n'th node
# in a linked list
# Node class
class Node:
# Function to initialise the node object
def __init__(self, data):
self.data = data # Assign data
self.next = None # Initialize next as null
# Linked List class contains a Node object
class LinkedList:
# Function to initialize head
def __init__(self):
self.head = None
# This function is in LinkedList class. It inserts
# a new node at the beginning of Linked List.
def push(self, new_data):
# 1 & 2: Allocate the Node &
# Put in the data
new_node = Node(new_data)
# 3. Make next of new Node as head
new_node.next = self.head
# 4. Move the head to point to new Node
self.head = new_node
# Returns data at given index in linked list
def getNth(self, index):
current = self.head # Initialise temp
count = 0 # Index of current node
# Loop while end of linked list is not reached
while (current):
if (count == index):
return current.data
count += 1
current = current.next
# if we get to this line, the caller was asking
# for a non-existent element so we assert fail
assert(false)
return 0
# Driver Code
if __name__ == '__main__':
llist = LinkedList()
# Use push() to construct below list
# 1->12->1->4->1
llist.push(1)
llist.push(4)
llist.push(1)
llist.push(12)
llist.push(1)
n = 3
print("Element at index 3 is :", llist.getNth(n))
C#
// C# program to find n'th node in linked list
using System;
using System.Diagnostics;
public class Node {
public int data;
public Node next;
public Node(int d)
{
data = d;
next = null;
}
}
class LinkedList {
Node head; // the head of list
/* Takes index as argument and return data at index*/
public int GetNth(int index)
{
Node current = head;
int count = 0; /* index of Node we are
currently looking at */
while (current != null) {
if (count == index)
return current.data;
count++;
current = current.next;
}
/* if we get to this line, the caller was asking
for a non-existent element so we assert fail */
Debug.Assert(false);
return 0;
}
/* Given a reference to the head of a list and an int,
inserts a new Node on the front of the list. */
public void push(int new_data)
{
/* 1. alloc the Node and put data*/
Node new_Node = new Node(new_data);
/* 2. Make next of new Node as head */
new_Node.next = head;
/* 3. Move the head to point to new Node */
head = new_Node;
}
/* Driver code*/
public static void Main(String[] args)
{
/* Start with empty list */
LinkedList llist = new LinkedList();
/* Use push() to construct below list
1->12->1->4->1 */
llist.push(1);
llist.push(4);
llist.push(1);
llist.push(12);
llist.push(1);
/* Check the count function */
Console.WriteLine("Element at index 3 is "
+ llist.GetNth(3));
}
}
// This code is contributed by Arnab Kundu
Javascript
<script>
// Javascript program to find n'th
// node in linked list
class Node {
constructor(d) {
this.data = d;
this.next = null;
}
}
var head; // the head of list
/* Takes index as argument and
return data at index */
function GetNth(index)
{
var current = head;
var count = 0;
/*
index of Node we are currently looking at
*/
while (current != null) {
if (count == index)
return current.data;
count++;
current = current.next;
}
/*
if we get to this line, the caller was asking
for a non-existent element so
we assert fail
*/
assert (false);
return 0;
}
/*
* Given a reference to the head of a
list and an int, inserts a new Node on the
front of the list.
*/
function push(new_data) {
/* 1. alloc the Node and put data */
var new_Node = new Node(new_data);
/* 2. Make next of new Node as head */
new_Node.next = head;
/* 3. Move the head to point to new Node */
head = new_Node;
}
/* Driver code */
/* Start with empty list */
/*
Use push() to construct below
list 1->12->1->4->1
*/
push(1);
push(4);
push(1);
push(12);
push(1);
/* Check the count function */
document.write("Element at index 3 is "
+ GetNth(3));
// This code is contributed by todaysgaurav
</script>
Producción
Element at index 3 is 4
Complejidad de tiempo: O(n)
Espacio auxiliar : espacio O(1) creado para variables
Método 2- Con recursividad
Este método es aportado por MY_DOOM .
Algoritmo:
Algorithm
getnth(node,n)
1. Initialize count = 0
2. if count==n
return node->data
3. else
return getnth(node->next,n-1)
Implementación:
C++
// C++ program to find n'th node in linked list
// using recursion
#include <bits/stdc++.h>
using namespace std;
/* Linked list node */
struct Node {
int data;
struct Node* next;
};
/* Given a reference (pointer to pointer) to
the head of a list and an int, push a
new node on the front of the list. */
void push(struct Node** head_ref, int new_data)
{
/* allocate node */
struct Node* new_node
= (struct Node*)malloc(sizeof(struct Node));
/* put in the data */
new_node->data = new_data;
/* link the old list off the new node */
new_node->next = (*head_ref);
/* move the head to point to the new node */
(*head_ref) = new_node;
}
/* Takes head pointer of the linked list and index
as arguments and return data at index. (Don't use
another variable)*/
int GetNth(struct Node* head, int n)
{
// if length of the list is less
// than the given index, return -1
if (head == NULL)
return -1;
// if n equal to 0 return node->data
if (n == 0)
return head->data;
// increase head to next pointer
// n - 1: decrease the number of recursions until n = 0
return GetNth(head->next, n - 1);
}
/* Driver code*/
int main()
{
/* Start with the empty list */
struct Node* head = NULL;
/* Use push() to construct below list
1->12->1->4->1 */
push(&head, 1);
push(&head, 4);
push(&head, 1);
push(&head, 12);
push(&head, 1);
/* Check the count function */
printf("Element at index 3 is %d", GetNth(head, 3));
getchar();
}
Java
// Java program to find n'th node in linked list
// using recursion
class GFG {
/* Linked list node */
static class Node {
int data;
Node next;
Node(int data) { this.data = data; }
}
/* Given a reference (pointer to pointer) to
the head of a list and an int, push a
new node on the front of the list. */
static Node push(Node head, int new_data)
{
/* allocate node */
Node new_node = new Node(new_data);
new_node.next = head;
head = new_node;
return head;
}
/* Takes head pointer of the linked list and index
as arguments and return data at index*/
static int GetNth(Node head, int n)
{
int count = 0;
if (head == null) // edge case - if head is null
return -1;
// if count equal too n return node.data
if (count == n)
return head.data;
// recursively decrease n and increase
// head to next pointer
return GetNth(head.next, n - 1);
}
/* Driver code*/
public static void main(String args[])
{
/* Start with the empty list */
Node head = null;
/* Use push() to construct below list
1.12.1.4.1 */
head = push(head, 1);
head = push(head, 4);
head = push(head, 1);
head = push(head, 12);
head = push(head, 1);
/* Check the count function */
System.out.printf("Element at index 3 is %d",
GetNth(head, 3));
}
}
// This code is contributed by Arnab Kundu
Python3
# Python3 program to find n'th node in
# linked list using recursion
class Node:
def __init__(self, data):
self.data = data
self.next = None
class LinkedList:
def __init__(self):
self.head = None
''' Given a reference (pointer to pointer) to the
head of a list and an int, push a new node on
the front of the list. '''
def push(self, new_data): # make new node and add
# into LinkedList
new_node = Node(new_data)
new_node.next = self.head
self.head = new_node
def getNth(self, llist, position):
# call recursive method
llist.getNthNode(self.head, position, llist)
# recursive method to find Nth Node
def getNthNode(self, head, position, llist):
count = 0 # initialize count
if(head):
if count == position: # if count is equal to position,
# it means we have found the position
print(head.data)
else:
llist.getNthNode(head.next, position - 1, llist)
else: # if head doesn't exist we have
# traversed the LinkedList
print('Index Doesn\'t exist')
# Driver Code
if __name__ == "__main__":
llist = LinkedList()
llist.push(1)
llist.push(4)
llist.push(1)
llist.push(12)
llist.push(1)
# llist.getNth(llist,int(input()))
# Enter the node position here
# first argument is instance of LinkedList
print("Element at Index 3 is", end=" ")
llist.getNth(llist, 3)
# This code is contributed by Yogesh Joshi
C#
// C# program to find n'th node in
// linked list using recursion
using System;
class GFG {
/* Link list node */
public class Node {
public int data;
public Node next;
public Node(int data) { this.data = data; }
}
/* Given a reference (pointer to pointer) to
the head of a list and an int, push a
new node on the front of the list. */
static Node push(Node head, int new_data)
{
/* allocate node */
Node new_node = new Node(new_data);
/* put in the data */
new_node.data = new_data;
new_node.next = head;
head = new_node;
return head;
}
/* Takes head pointer of the linked list and index
as arguments and return data at index*/
static int GetNth(Node head, int n)
{
// Base Condition
if (head == null)
return -1;
int count = 0;
// if count equal too n return node.data
// Test Condition
if (count == n)
return head.data;
// recursively decrease n and increase
// head to next pointer
return GetNth(head.next, n - 1);
}
/* Driver code*/
public static void Main()
{
/* Start with the empty list */
Node head = null;
/* Use push() to construct below list
1.12.1.4.1 */
head = push(head, 1);
head = push(head, 4);
head = push(head, 1);
head = push(head, 12);
head = push(head, 1);
/* Check the count function */
Console.Write("Element at index 3 is {0}",
GetNth(head, 3));
}
}
/*Code improvement by Aishwarya Mittal*/
/* This code contributed by PrinciRaj1992 */
Javascript
<script>
// javascript program to find n'th node in linked list
// using recursion /* Link list node */
class Node {
constructor(val) {
this.data = val;
this.next = null;
}
}
/*
* Given a reference (pointer to pointer) to the head of a list and an int, push
* a new node on the front of the list.
*/
function push(head , new_data) {
/* allocate node */
var new_node = new Node(new_data);
/* put in the data */
new_node.data = new_data;
new_node.next = head;
head = new_node;
return head;
}
/*
* Takes head pointer of the linked list and index as arguments and return data
* at index
*/
function GetNth(head , n) {
var count = 0;
if (head == null) // edge case - if head is null
return -1;
// if count equal too n return node.data
if (count == n)
return head.data;
// recursively decrease n and increase
// head to next pointer
return GetNth(head.next, n - 1);
}
/* Driver code */
/* Start with the empty list */
var head = null;
/*
* Use push() to construct below list 1.12.1.4.1
*/
head = push(head, 1);
head = push(head, 4);
head = push(head, 1);
head = push(head, 12);
head = push(head, 1);
/* Check the count function */
document.write("Element at index 3 is ", GetNth(head, 3));
// This code contributed by gauravrajput1
</script>
Producción
Element at index 3 is 4
Complejidad de Tiempo : O(n) Espacio Auxiliar : O(n) debido a llamadas recursivas.
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Publicación traducida automáticamente
Artículo escrito por GeeksforGeeks-1 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA