[LeetCode] Problem 19 - Remove Nth Node From End of List

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Given a linked list, remove the nth node from the end of list and return its head.

Example

Given linked list: 1->2->3->4->5, and n = 2.

After removing the second node from the end, the linked list becomes 1->2->3->5.

Note

Given n will always be valid.

Follow up

Could you do this in one pass?

Code

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public class ListNode {
    int val;
    ListNode next = null;
    ListNode(int x) { val = x; }
}
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public ListNode removeNthFromEnd(ListNode head, int n) {
    ListNode dummy = new ListNode(0);
    dummy.next = head;
    ListNode slow = dummy;
    ListNode fast = dummy;

    for (int i = 0; i < n; i++)
        fast = fast.next;

    while (fast.next != null) {
        fast = fast.next;
        slow = slow.next;
    }

    slow.next = slow.next.next;

    return dummy.next;
}