1290. Convert Binary Number in a Linked List to Integer

[Tcdian]

1290. Convert Binary Number in a Linked List to Integer

Given head which is a reference node to a singly-linked list. The value of each node in the linked list is either 0 or 1. The linked list holds the binary representation of a number.

Return the decimal value of the number in the linked list.

Example 1

Input: head = [1,0,1]
Output: 5
Explanation: (101) in base 2 = (5) in base 10```

#### Example 2

```text
Input: head = [0]
Output: 0

Example 3

Input: head = [1]
Output: 1

Example 4

Input: head = [1,0,0,1,0,0,1,1,1,0,0,0,0,0,0]
Output: 18880

Example 5

Input: head = [0,0]
Output: 0

Constraints

• The Linked List is not empty.
• Number of nodes will not exceed 30.
• Each node's value is either 0 or 1.

[Tcdian]

Solution

• TypeScript Solution

/**
 * Definition for singly-linked list.
 * class ListNode {
 *     val: number
 *     next: ListNode | null
 *     constructor(val?: number, next?: ListNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.next = (next===undefined ? null : next)
 *     }
 * }
 */

function getDecimalValue(head: ListNode | null): number {
    let result = 0;
    let digits = 0;
    let patrol = head;
    while (patrol !== null) {
        digits++;
        patrol = patrol.next;
    }
    patrol = head;
    while (patrol !== null) {
        result += patrol.val * Math.pow(2, --digits);
        patrol = patrol.next;
    }
    return result;
};