Data commit

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

@@ -0,0 +1,13 @@
+rlcs(_ s1: String, _ s2: String) -> String {
+   if s1.count == 0 || s2.count == 0 {
+       return ""
+   } else if s1[s1.index(s1.endIndex, offsetBy: -1)] == s2[s2.index(s2.endIndex, offsetBy: -1)] {
+       return rlcs(String(s1[s1.startIndex..<s1.index(s1.endIndex, offsetBy: -1)]),
+                   String(s2[s2.startIndex..<s2.index(s2.endIndex, offsetBy: -1)])) + String(s1[s1.index(s1.endIndex, offsetBy: -1)])
+   } else {
+       let str1 = rlcs(s1, String(s2[s2.startIndex..<s2.index(s2.endIndex, offsetBy: -1)]))
+       let str2 = rlcs(String(s1[s1.startIndex..<s1.index(s1.endIndex, offsetBy: -1)]), s2)
+
+       return str1.count > str2.count ? str1 : str2
+   }
+}

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

@@ -0,0 +1,33 @@
+func lcs(_ s1: String, _ s2: String) -> String {
+    var lens = Array(
+        repeating:Array(repeating: 0, count: s2.count + 1),
+        count: s1.count + 1
+    )
+
+    for i in 0..<s1.count {
+        for j in 0..<s2.count {
+            if s1[s1.index(s1.startIndex, offsetBy: i)] == s2[s2.index(s2.startIndex, offsetBy: 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])
+            }
+        }
+    }
+
+    var returnStr = ""
+    var x = s1.count
+    var y = s2.count
+    while x != 0 && y != 0 {
+        if lens[x][y] == lens[x - 1][y] {
+            x -= 1
+        } else if lens[x][y] == lens[x][y - 1] {
+            y -= 1
+        } else {
+            returnStr += String(s1[s1.index(s1.startIndex, offsetBy:  x - 1)])
+            x -= 1
+            y -= 1
+        }
+    }
+
+    return String(returnStr.reversed())
+}