Create: 19-Remove-Nth-Node-From-End-of-List.swift

Author: Ykhan799

swift/19-Remove-Nth-Node-From-End-of-List.swift

@@ -0,0 +1,31 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     public var val: Int
+ *     public var next: ListNode?
+ *     public init() { self.val = 0; self.next = nil; }
+ *     public init(_ val: Int) { self.val = val; self.next = nil; }
+ *     public init(_ val: Int, _ next: ListNode?) { self.val = val; self.next = next; }
+ * }
+ */
+class Solution {
+    func removeNthFromEnd(_ head: ListNode?, _ n: Int) -> ListNode? {
+        if head === nil {
+            return head
+        }
+        var slow = head, fast = head
+        for i in 1...n + 1 {
+            if (slow === nil) {
+                return head?.next
+            }
+            slow = slow?.next
+        }
+        
+        while slow != nil {
+            slow = slow?.next
+            fast = fast?.next
+        }
+        fast?.next = fast?.next?.next
+        return head
+    }
+}