1 files changed, 153 insertions, 0 deletions
diff --git a/challenge-071/mohammad-anwar/swift/ch-2.swift b/challenge-071/mohammad-anwar/swift/ch-2.swift
new file mode 100644
index 0000000000..384a0d70c9
--- /dev/null
+++ b/challenge-071/mohammad-anwar/swift/ch-2.swift
@@ -0,0 +1,153 @@
+import Foundation
+
+/*
+
+Perl Weekly Challenge - 071
+
+Task #2: Trim Linked List
+
+https://perlweeklychallenge.org/blog/perl-weekly-challenge-071/
+
+*/
+
+class Node {
+    var v:Int
+    var p:Node?
+
+    init(value: Int) {
+        v = value
+    }
+
+    func trim(_ position: Int) -> Node {
+        var tail:Node = self
+        var count:Int = 1
+        var node:Node = Node(value: 0)
+
+        while tail.p != nil {
+            if position > count {
+                node = tail
+            }
+            else if position == count {
+                if node.v != 0 {
+                    node.p = tail.p!
+                }
+                else {
+                    return tail.p!
+                }
+            }
+
+            tail = tail.p!
+            count += 1
+        }
+
+        if count <= position {
+            node.p = nil
+        }
+
+        return self
+    }
+
+    func show() -> String {
+
+        var node:Node = self
+        var v = [String]()
+
+        while node.p != nil {
+            v.append(String(node.v))
+            node = node.p!
+        }
+        v.append(String(node.v))
+
+        v = v.reversed()
+
+        return v.joined(separator: ", ")
+    }
+
+    class func createLinkedList(_ list:String) -> Node {
+
+        let _list = list.replacingOccurrences(
+                    of: " ",
+                    with: "",
+                    options: .literal,
+                    range: nil)
+
+        var array  = _list.components(separatedBy: ",")
+        let n:Node = Node(value: Int(array.removeLast())!)
+        var t:Node = n
+
+        while array.count >= 1 {
+            let _n:Node = Node(value: Int(array.removeLast())!)
+            t.p  = _n
+            t    = _n
+        }
+
+        return n
+    }
+}
+
+enum ParamError: Error {
+    case missingList
+    case missingPosition
+    case invalidList
+    case invalidPosition
+}
+
+do {
+    let paramCount:Int = Int(CommandLine.argc)
+
+    if paramCount <= 1 {
+        throw ParamError.missingList
+    }
+
+    if paramCount <= 2 {
+        throw ParamError.missingPosition
+    }
+
+    let list:String  = CommandLine.arguments[1]
+    let position:Int = Int(CommandLine.arguments[2])!
+
+    if isValidList(list) {
+        if position >= 1 {
+            print(Node.createLinkedList(list).trim(position).show())
+        }
+        else {
+            throw ParamError.invalidPosition
+        }
+    }
+    else {
+        throw ParamError.invalidList
+    }
+}
+catch ParamError.missingList {
+    print("Missing list.")
+}
+catch ParamError.missingPosition {
+    print("Missing position.")
+}
+catch ParamError.invalidList {
+    print("Invalid list.")
+}
+catch ParamError.invalidPosition {
+    print("Invalid position.")
+}
+catch let error {
+    print(error)
+}
+
+//
+//
+// Functions
+
+func isValidList(_ list:String) -> Bool {
+
+    let pattern = "^[\\-?\\d\\,?\\s?]+$"
+    let regex   = try! NSRegularExpression(pattern: pattern)
+    let range   = NSRange(location: 0, length: list.utf16.count)
+
+    if regex.firstMatch(in: list, options: [], range: range) != nil {
+        return true
+    }
+    else {
+        return false
+    }
+}