g0201_0300.s0206_reverse_linked_list.Solution.py Maven / Gradle / Ivy

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104 LeetCode algorithm problem solutions

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# #Easy #Top_100_Liked_Questions #Top_Interview_Questions #Linked_List #Recursion
# #Data_Structure_I_Day_8_Linked_List #Algorithm_I_Day_10_Recursion_Backtracking
# #Level_1_Day_3_Linked_List #Udemy_Linked_List #Big_O_Time_O(N)_Space_O(1)
# #2024_06_09_Time_35_ms_(72.56%)_Space_17.6_MB_(68.68%)

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def reverseList(self, head: Optional[ListNode]) -> Optional[ListNode]:
        prev = None
        curr = head
        while curr is not None:
            next_node = curr.next
            curr.next = prev
            prev = curr
            curr = next_node
        return prev