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package g0201_0300.s0206_reverse_linked_list;

// #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_11_15_Time_0_ms_(100.00%)_Space_42.5_MB_(41.63%)

import com_github_leetcode.ListNode;

/*
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
public class Solution {
    public ListNode reverseList(ListNode head) {
        ListNode prev = null;
        ListNode curr = head;
        while (curr != null) {
            ListNode next = curr.next;
            curr.next = prev;
            prev = curr;
            curr = next;
        }
        return prev;
    }
}