Add tasks for all the new languages

Task/Longest-common-subsequence/Swift/longest-common-subsequence-1.swift

@@ -0,0 +1,16 @@
+func rlcs(s1:String, _ s2:String) -> String {
+    let x = s1.characters.count
+    let y = s2.characters.count
+
+    if x == 0 || y == 0 {
+        return ""
+    } else if s1[s1.startIndex.advancedBy(x - 1)] == s2[s2.startIndex.advancedBy(y - 1)] {
+        return rlcs(s1[s1.startIndex..<s1.startIndex.advancedBy(x - 1)],
+            s2[s2.startIndex..<s2.startIndex.advancedBy(y - 1)]) + String(s1[s1.startIndex.advancedBy(x - 1)])
+    } else {
+        let xstr = rlcs(s1, s2[s2.startIndex..<s2.startIndex.advancedBy(y - 1)])
+        let ystr = rlcs(s1[s1.startIndex..<s1.startIndex.advancedBy(x - 1)], s2)
+
+        return xstr.characters.count > ystr.characters.count ? xstr : ystr
+    }
+}

Task/Longest-common-subsequence/Swift/longest-common-subsequence-2.swift

@@ -0,0 +1,31 @@
+func lcs(s1:String, _ s2:String) -> String {
+    var x = s1.characters.count
+    var y = s2.characters.count
+    var lens = Array(count: x + 1, repeatedValue:
+        Array(count: y + 1, repeatedValue: 0))
+    var returnStr = ""
+
+    for i in 0..<x {
+        for j in 0..<y {
+            if s1[s1.startIndex.advancedBy(i)] == s2[s2.startIndex.advancedBy(j)] {
+                lens[i + 1][j + 1] = lens[i][j] + 1
+            } else {
+                lens[i + 1][j + 1] = max(lens[i + 1][j], lens[i][j + 1])
+            }
+        }
+    }
+
+    while x != 0 && y != 0 {
+        if lens[x][y] == lens[x - 1][y] {
+            --x
+        } else if lens[x][y] == lens[x][y - 1] {
+            --y
+        } else {
+            returnStr += String(s1[s1.startIndex.advancedBy(x - 1)])
+            --x
+            --y
+        }
+    }
+
+    return String(returnStr.characters.reverse())
+}