feat: add solutions to lc problem: No.0019 (#3901)

No.0019.Remove Nth Node From End of List
doocs · Dec 30, 2024 · 2f30bab · 2f30bab
1 parent 66e1a30
commit 2f30bab
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diff --git a/solution/0000-0099/0019.Remove Nth Node From End of List/README.md b/solution/0000-0099/0019.Remove Nth Node From End of List/README.md
@@ -278,6 +278,38 @@ var removeNthFromEnd = function (head, n) {
 };
 ```
 
+#### Swift
+
+````swift
+/**
+ * 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? {
+        let dummy = ListNode(0)
+        dummy.next = head
+        var fast: ListNode? = dummy
+        var slow: ListNode? = dummy
+        for _ in 0..<n {
+            fast = fast?.next
+        }
+        while fast?.next != nil {
+            fast = fast?.next
+            slow = slow?.next
+        }
+        slow?.next = slow?.next?.next
+        return dummy.next
+    }
+}
+```
+
 #### Ruby
 
 ```rb
@@ -311,43 +343,34 @@ end
 #### PHP
 
 ```php
-# Definition for singly-linked list.
-# class ListNode {
-#     public $val;
-#     public $next;
-
-#     public function __construct($val = 0, $next = null)
-#     {
-#         $this->val = $val;
-#         $this->next = $next;
-#     }
-# }
-
+/**
+ * Definition for a singly-linked list.
+ * class ListNode {
+ *     public $val = 0;
+ *     public $next = null;
+ *     function __construct($val = 0, $next = null) {
+ *         $this->val = $val;
+ *         $this->next = $next;
+ *     }
+ * }
+ */
 class Solution {
     /**
      * @param ListNode $head
-     * @param int $n
+     * @param Integer $n
      * @return ListNode
      */
-
     function removeNthFromEnd($head, $n) {
-        $dummy = new ListNode(0);
-        $dummy->next = $head;
-
-        $first = $dummy;
-        $second = $dummy;
-
-        for ($i = 0; $i <= $n; $i++) {
-            $second = $second->next;
+        $dummy = new ListNode(0, $head);
+        $fast = $slow = $dummy;
+        for ($i = 0; $i < $n; $i++) {
+            $fast = $fast->next;
         }
-
-        while ($second != null) {
-            $first = $first->next;
-            $second = $second->next;
+        while ($fast->next !== null) {
+            $fast = $fast->next;
+            $slow = $slow->next;
         }
-
-        $first->next = $first->next->next;
-
+        $slow->next = $slow->next->next;
         return $dummy->next;
     }
 }
@@ -358,3 +381,4 @@ class Solution {
 <!-- solution:end -->
 
 <!-- problem:end -->
+````
diff --git a/solution/0000-0099/0019.Remove Nth Node From End of List/README_EN.md b/solution/0000-0099/0019.Remove Nth Node From End of List/README_EN.md
@@ -275,6 +275,38 @@ var removeNthFromEnd = function (head, n) {
 };
 ```
 
+#### Swift
+
+````swift
+/**
+ * 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? {
+        let dummy = ListNode(0)
+        dummy.next = head
+        var fast: ListNode? = dummy
+        var slow: ListNode? = dummy
+        for _ in 0..<n {
+            fast = fast?.next
+        }
+        while fast?.next != nil {
+            fast = fast?.next
+            slow = slow?.next
+        }
+        slow?.next = slow?.next?.next
+        return dummy.next
+    }
+}
+```
+
 #### Ruby
 
 ```rb
@@ -308,43 +340,34 @@ end
 #### PHP
 
 ```php
-# Definition for singly-linked list.
-# class ListNode {
-#     public $val;
-#     public $next;
-
-#     public function __construct($val = 0, $next = null)
-#     {
-#         $this->val = $val;
-#         $this->next = $next;
-#     }
-# }
-
+/**
+ * Definition for a singly-linked list.
+ * class ListNode {
+ *     public $val = 0;
+ *     public $next = null;
+ *     function __construct($val = 0, $next = null) {
+ *         $this->val = $val;
+ *         $this->next = $next;
+ *     }
+ * }
+ */
 class Solution {
     /**
      * @param ListNode $head
-     * @param int $n
+     * @param Integer $n
      * @return ListNode
      */
-
     function removeNthFromEnd($head, $n) {
-        $dummy = new ListNode(0);
-        $dummy->next = $head;
-
-        $first = $dummy;
-        $second = $dummy;
-
-        for ($i = 0; $i <= $n; $i++) {
-            $second = $second->next;
+        $dummy = new ListNode(0, $head);
+        $fast = $slow = $dummy;
+        for ($i = 0; $i < $n; $i++) {
+            $fast = $fast->next;
         }
-
-        while ($second != null) {
-            $first = $first->next;
-            $second = $second->next;
+        while ($fast->next !== null) {
+            $fast = $fast->next;
+            $slow = $slow->next;
         }
-
-        $first->next = $first->next->next;
-
+        $slow->next = $slow->next->next;
         return $dummy->next;
     }
 }
@@ -355,3 +378,4 @@ class Solution {
 <!-- solution:end -->
 
 <!-- problem:end -->
+````
diff --git a/solution/0000-0099/0019.Remove Nth Node From End of List/Solution.php b/solution/0000-0099/0019.Remove Nth Node From End of List/Solution.php
@@ -1,40 +1,31 @@
-# Definition for singly-linked list.
-# class ListNode {
-#     public $val;
-#     public $next;
-
-#     public function __construct($val = 0, $next = null)
-#     {
-#         $this->val = $val;
-#         $this->next = $next;
-#     }
-# }
-
+/**
+ * Definition for a singly-linked list.
+ * class ListNode {
+ *     public $val = 0;
+ *     public $next = null;
+ *     function __construct($val = 0, $next = null) {
+ *         $this->val = $val;
+ *         $this->next = $next;
+ *     }
+ * }
+ */
 class Solution {
     /**
      * @param ListNode $head
-     * @param int $n
+     * @param Integer $n
      * @return ListNode
      */
-
     function removeNthFromEnd($head, $n) {
-        $dummy = new ListNode(0);
-        $dummy->next = $head;
-
-        $first = $dummy;
-        $second = $dummy;
-
-        for ($i = 0; $i <= $n; $i++) {
-            $second = $second->next;
+        $dummy = new ListNode(0, $head);
+        $fast = $slow = $dummy;
+        for ($i = 0; $i < $n; $i++) {
+            $fast = $fast->next;
         }
-
-        while ($second != null) {
-            $first = $first->next;
-            $second = $second->next;
+        while ($fast->next !== null) {
+            $fast = $fast->next;
+            $slow = $slow->next;
         }
-
-        $first->next = $first->next->next;
-
+        $slow->next = $slow->next->next;
         return $dummy->next;
     }
 }
diff --git a/solution/0000-0099/0019.Remove Nth Node From End of List/Solution.swift b/solution/0000-0099/0019.Remove Nth Node From End of List/Solution.swift
@@ -0,0 +1,27 @@
+/**
+ * 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? {
+        let dummy = ListNode(0)
+        dummy.next = head
+        var fast: ListNode? = dummy
+        var slow: ListNode? = dummy
+        for _ in 0..<n {
+            fast = fast?.next
+        }
+        while fast?.next != nil {
+            fast = fast?.next
+            slow = slow?.next
+        }
+        slow?.next = slow?.next?.next
+        return dummy.next
+    }
+}