Write a function that searches a given key ‘x’ in a given singly linked list. The function should return true if x is present in linked list and false otherwise.
bool search(Node *head, int x)
For example, if the key to be searched is 15 and linked list is 14->21->11->30->10, then function should return false. If key to be searched is 14, then the function should return true.
Iterative Solution:
1) Initialize a node pointer, current = head.
2) Do following while current is not NULL
a) current->key is equal to the key being searched return true.
b) current = current->next
3) Return false
Following is iterative implementation of above algorithm to search a given key.
Javascript
<script>// Iterative javascript program // to search an element// in linked list//Node classclass Node { constructor(d) { this.data = d; this.next = null; }}// Linked list class// Head of listvar head; // Inserts a new node at the front of the listfunction push(new_data){ // Allocate new node and putting data var new_node = new Node(new_data); // Make next of new node as head new_node.next = head; // Move the head to point to new Node head = new_node;}// Checks whether the value // x is present in linked listfunction search(head , x) { // Initialize current var current = head; while (current != null) { if (current.data == x) // Data found return true; current = current.next; } // Data not found return false; }// Driver code // Start with the empty list// Use push() to construct list// 14->21->11->30->10push(10);push(30);push(11);push(21);push(14);if (search(head, 21)) document.write("Yes");else document.write("No");// This code contributed by aashish1995</script> |
Output:
Yes
Time Complexity: O(n), where n represents the length of the given linked list.
Auxiliary Space: O(1), no extra space is required, so it is a constant.
Recursive Solution:
bool search(head, x) 1) If head is NULL, return false. 2) If head's key is same as x, return true; 3) Else return search(head->next, x)
Following is the recursive implementation of the above algorithm to search a given key.
Javascript
<script>// Recursive javascript program to search // an element in linked list// Node classclass Node{ constructor(val) { this.data = val; this.next = null; }} // Linked list class// Head of listvar head; // Inserts a new node at the front // of the listfunction push(new_data) { // Allocate new node and putting data var new_node = new Node(new_data); // Make next of new node as head new_node.next = head; // Move the head to point to new Node head = new_node;}// Checks whether the value x is present// in linked listfunction search(head, x) { // Base case if (head == null) return false; // If key is present in current node, // return true if (head.data == x) return true; // Recur for remaining list return search(head.next, x);}// Driver code // Start with the empty list// Use push() to construct list // 14->21->11->30->10push(10);push(30);push(11);push(21);push(14);if (search(head, 21)) document.write("Yes"); else document.write("No");// This code contributed by gauravrajput1 </script> |
Output:
Yes
Time Complexity: O(n), where n represents the length of the given linked list.
Auxiliary Space: O(n), for recursive stack where n represents the length of the given linked list.
Please refer complete article on Search an element in a Linked List (Iterative and Recursive) for more details!
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