JavaScript Exercises: Find the first index that matches a given element
JavaScript Singly Linked List: Exercise-8 with Solution
Find the first index that matches a given element
Write a JavaScript program to find the first index that matches a given element. Return -1 for no matching.
Sample Solution:
JavaScript Code:
// Define a class representing a node in a singly linked list
class Node {
constructor(data) {
// Initialize the node with provided data
this.data = data
// Initialize the next pointer to null
this.next = null
}
}
// Define a class representing a singly linked list
class SinglyLinkedList {
constructor(Head = null) {
// Initialize the head of the list
this.Head = Head
}
// Method to add a new node to the end of the list
add(newNode){
// Start traversal from the head node
let node = this.Head;
// If the list is empty, set the new node as the head and return
if(node == null){
this.Head = newNode;
return;
}
// Traverse the list until the last node
while (node.next) {
node = node.next;
}
// Set the next pointer of the last node to the new node
node.next = newNode;
}
// Method to find the index of the first occurrence of a value in the list
indexOf(data){
// Initialize the index variable to -1
let ind = -1;
// Start traversal from the head node
let node = this.Head;
// Traverse the list
while(node){
// Increment the index
++ind;
// If the data of the current node matches the target data, return the index
if(node.data === data) return ind;
// Move to the next node
node = node.next;
}
// If the target data is not found, return -1
return -1;
}
// Method to display the elements of the list
displayList(){
// Start traversal from the head node
let node = this.Head;
// Initialize an empty string to store the elements of the list
var str = ""
// Traverse the list and concatenate each element to the string
while (node) {
str += node.data + "->";
node = node.next;
}
// Append "NULL" to indicate the end of the list
str += "NULL"
// Print the string containing the list elements
console.log(str);
}
}
// Create an instance of the SinglyLinkedList class
let numList = new SinglyLinkedList();
// Add nodes with data values to the list
numList.add(new Node(12));
numList.add(new Node(13));
numList.add(new Node(14));
numList.add(new Node(15));
numList.add(new Node(14));
// Display the elements of the list
console.log("Original Linked list:");
numList.displayList();
// Find the index of the first occurrence of value 14 in the list
console.log("Find the first index that matches the value 14:");
console.log(numList.indexOf(14));
// Find the index of the first occurrence of value 5 in the list
console.log("Find the first index that matches the value 5:");
console.log(numList.indexOf(5));
Output:
12->13->14->15->14->NULL Find the first index that matches the value 14: 2 Find the first index that matches the value 5: -1
Flowchart:
Live Demo:
See the Pen javascript-singly-linked-list-exercise-8 by w3resource (@w3resource) on CodePen.
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Singly Linked List Previous: Get a node in an existing singly linked list.
Singly Linked List Next: Check whether a single linked list is empty or not.
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