Javascript Program To Find Decimal Equivalent Of Binary Linked List

Last Updated : 03 Sep, 2024

Given a singly linked list of 0s and 1s find its decimal equivalent.

Input: 0->0->0->1->1->0->0->1->0
Output: 50   

Input: 1->0->0
Output: 4

The decimal value of an empty linked list is considered as 0.

Initialize the result as 0. Traverse the linked list and for each node, multiply the result by 2 and add the node's data to it.

JavaScript

// Javascript Program to find decimal value  // of binary linked list       // Link list Node class Node {     constructor() {         this.data = true;         this.next = null;     } }  // Returns decimal value of binary  // linked list  function decimalValue(head) {     // Initialized result     let res = 0;      // Traverse linked list     while (head != null) {         // Multiply result by 2 and add         // head's data         res = (res << 1) +             (head.data ? 1 : 0);          // Move next         head = head.next;     }     return res; }  // Utility function to create a  // new node. function newNode(data) {     let temp = new Node();     temp.data = (data == 1 ?         true : false);     temp.next = null;     return temp; }  // Driver code  // Start with the empty list  let head = newNode(1); head.next = newNode(0); head.next.next = newNode(1); head.next.next.next = newNode(1); console.log("Decimal value is " + decimalValue(head)); // This code is contributed by aashish1995

Output

Decimal value is 11

Complexity Analysis:

Time Complexity: O(n) where n is the number of nodes in the given linked list.
Auxiliary Space: O(1), no extra space is required, so it is a constant.

Another Approach(by reversing the Linked List):

Follow the below steps to solve the given problem

First reverse the given linked list.
Initialize a ans variable to store ans and pos variable to keep track of position of node in linked list.
Perform the operation ans = ans + (rhead.data*(2**pos))%MOD)
perform ans = ans%MOD

Below is the implementation of above approach:

JavaScript

// JavaScript program to find the decimal value // of binary linked list // node class class Node{     constructor(data){         this.data = data;         this.left = null;         this.right = null;     } }  function reverse(head){     if(head == null || head.next == null) return head;          let curr = head;     let prev = null;     let nxt = head.next;     while(nxt != null){         curr.next = prev;         prev = curr;         curr = nxt;         nxt = nxt.next;     }     curr.next = prev;     return curr; }  function decimalValue(head){     let MOD = 1000000007;     let rhead = reverse(head);          let ans = 0;     let pos = 0;     while(rhead != null){         ans = (ans % MOD+(rhead.data*(2**pos)) % MOD) % MOD;         rhead = rhead.next;         pos += 1;     }     return ans; }  // driver program to test above function let head = new Node(1); head.next = new Node(0); head.next.next = new Node(1); head.next.next.next= new Node(1);  console.log("Decimal Value is : " + decimalValue(head));