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:

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.

这题还是很简单的，首先要熟悉单项链表的遍历，然后熟悉二进制的表达。我们从头节点开始遍历，然后每次遍历一次都需要乘二，把之前的结果往前挪一位，也算进位。

class ConvertBinaryNumberInALinkedListToInteger : public Solution {
public:
    void Exec() {

    }
    int getDecimalValue(ListNode* head) {
        int decimal = 0;
        ListNode *node = head;
        while (nullptr != node) {
            decimal *= 2;
            decimal += node->val;
            node = node->next;
        }
        return decimal;
    }
};