1290: Convert-Binary-Number-in-a-Linked-List-to-Integer
Easy

table of contents

We can simply iterate through the linked list and left shift our answer after every iteration, adding 1 depending on what the bit is.

Using [0, 1, 0, 1] as an example, we have:

code

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    int getDecimalValue(ListNode* head) {
        int ans = 0;
        while (head != NULL) {
            ans *= 2;
            ans += head->val;
            head = head->next;
        }
        return ans;
    }
};

complexity

time taken