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Reverse a linked list

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Given the head of a singly linked list, reverse the list, and return the reversed list.

public ListNode reverseList(ListNode head) {
    /* iterative solution */
    ListNode newHead = null;
    while (head != null) {
        ListNode next = head.next;
        head.next = newHead;
        newHead = head;
        head = next;
    }
    return newHead;
}

public ListNode reverseList(ListNode head) {
    /* recursive solution */
    return reverseListInt(head, null);
}

private ListNode reverseListInt(ListNode head, ListNode newHead) {
    if (head == null)
        return newHead;
    ListNode next = head.next;
    head.next = newHead;
    return reverseListInt(next, head);
}

Posted by Jamie Meyer 4 months ago

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