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2020-11-01
1290. Convert Binary Number in a Linked List to Integer
Question:
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:
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
0or1.
Solution:
Shift the result to left by 1 and add the node value in to the last binary in result.
/**
* 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 result = 0;
while (head != null) {
result = result << 1;
result += head.val;
head = head.next;
}
return result;
}
}
Similar solution
/**
* 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) {
ListNode curr = head;
int result = 0;
while(curr != null) {
result = (result << 1) | curr.val;
curr = curr.next;
}
return result;
}
}