LeetCode - Algorithms - 1290. Convert Binary Number in a Linked List to Integer

Problem

1290. Convert Binary Number in a Linked List to Integer

Java

Bit Manipulation

© Approach 2: Bit Manipulation

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/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public int getDecimalValue(ListNode head) {
        if (head == null)
            return 0;
        int d = head.val;
        while (head.next != null) {
            d = (d << 1) | head.next.val;
            head = head.next;
        }
        return d;
    }
}

Submission Detail

  • 102 / 102 test cases passed.
  • Runtime: 0 ms, faster than 100.00% of Java online submissions for Convert Binary Number in a Linked List to Integer.
  • Memory Usage: 36.4 MB, less than 11.21% of Java online submissions for Convert Binary Number in a Linked List to Integer.

my solution

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/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public int getDecimalValue(ListNode head) {
        int n = 0;
        ListNode node = head;
        while (node != null) {
            n++;
            node = node.next;
        }
        node = head;
        int x = 0;
        for (int i = n - 1; i > 0; i--) {
            x += node.val * (2 << (i - 1));
            node = node.next;
        }
        x += node.val;
        return x;
    }
}

Submission Detail

  • 102 / 102 test cases passed.
  • Runtime: 0 ms, faster than 100.00% of Java online submissions for Convert Binary Number in a Linked List to Integer.
  • Memory Usage: 36.4 MB, less than 10.97% of Java online submissions for Convert Binary Number in a Linked List to Integer.