1290. 二进制链表转整数

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */


int getDecimalValue(struct ListNode* head){
    int count = 0;
    struct ListNode* p = head;
    while(p)
    {
        count++;
        p = p->next;
    }

    int sum = 0;
    count--;
    while(head)
    {
            sum += (head->val )*(int)(pow(2,count)); 
            head = head->next;
            count--;
    }


    return sum;
}