feat: add swift implementation to lcci problem: No.02.04 (#2617)

Signed-off-by: Lanre Adedara

Author: klever34

lcci/02.04.Partition List/README.md

@@ -201,6 +201,44 @@ function partition(head: ListNode | null, x: number): ListNode | null {
 }
 ```
 
+```swift
+/** public class ListNode {
+*    var val: Int
+*    var next: ListNode?
+*    init(_ x: Int) {
+*        self.val = x
+*        self.next = nil
+*    }
+* }
+*/
+
+class Solution {
+    func partition(_ head: ListNode?, _ x: Int) -> ListNode? {
+        let leftDummy = ListNode(0)
+        let rightDummy = ListNode(0)
+        var left = leftDummy
+        var right = rightDummy
+        var head = head
+
+        while let current = head {
+            if current.val < x {
+                left.next = current
+                left = left.next!
+            } else {
+                right.next = current
+                right = right.next!
+            }
+            head = head?.next
+        }
+
+        right.next = nil
+        left.next = rightDummy.next
+
+        return leftDummy.next
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/02.04.Partition List/README_EN.md

@@ -179,6 +179,44 @@ function partition(head: ListNode | null, x: number): ListNode | null {
 }
 ```
 
+```swift
+/** public class ListNode {
+*    var val: Int
+*    var next: ListNode?
+*    init(_ x: Int) {
+*        self.val = x
+*        self.next = nil
+*    }
+* }
+*/
+
+class Solution {
+    func partition(_ head: ListNode?, _ x: Int) -> ListNode? {
+        let leftDummy = ListNode(0)
+        let rightDummy = ListNode(0)
+        var left = leftDummy
+        var right = rightDummy
+        var head = head
+
+        while let current = head {
+            if current.val < x {
+                left.next = current
+                left = left.next!
+            } else {
+                right.next = current
+                right = right.next!
+            }
+            head = head?.next
+        }
+
+        right.next = nil
+        left.next = rightDummy.next
+
+        return leftDummy.next
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/02.04.Partition List/Solution.swift

@@ -0,0 +1,35 @@
+/** public class ListNode {
+*    var val: Int
+*    var next: ListNode?
+*    init(_ x: Int) {
+*        self.val = x
+*        self.next = nil
+*    }
+* }
+*/
+
+class Solution {
+    func partition(_ head: ListNode?, _ x: Int) -> ListNode? {
+        let leftDummy = ListNode(0)
+        let rightDummy = ListNode(0)
+        var left = leftDummy
+        var right = rightDummy
+        var head = head
+        
+        while let current = head {
+            if current.val < x {
+                left.next = current
+                left = left.next!
+            } else {
+                right.next = current
+                right = right.next!
+            }
+            head = head?.next
+        }
+        
+        right.next = nil
+        left.next = rightDummy.next
+        
+        return leftDummy.next
+    }
+}