[leetCode] 1290. Convert Binary Number in a Linked List to Integer (Python)

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.

 

 

Solution

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def getDecimalValue(self, head: ListNode) -> int:
        binary_nums = []
        
        while head != None:
            binary_nums.append(str(head.val))
            head = head.next
            
        bin_num = "".join(binary_nums)
        
        return int(bin_num, 2)

Solution 해설

먼저 linked list에 있는 모든 수를 binary_nums 리스트에 저장합니다.

저장할때는 int 형식을 str 형식으로 변환하여 저장합니다.

binary_nums를 join을 활용하여 하나의 이진수 문자열로 만들어줍니다.

마지막으로 int를 활용하여 10진수로 변환해주면 됩니다.

SOMJANG/CODINGTEST_PRACTICE