subStrings.Swift

extension Sliceable where Generator.Element : Equatable, Index.Distance == Int {
  func lComSubStr<
    S: Sliceable where
    S.Generator.Element == Generator.Element,
    S.Index.Distance == Int
    >(with: S) -> SubSlice {
      
      var (len, end) = (0, 0)
      
      let empty = Array(Repeat(count: with.count + 1, repeatedValue: 0))
      var mat: [[Int]] = Array(Repeat(count: self.count + 1, repeatedValue: empty))
      
      for (i, sLett) in self.enumerate() {
        for (j, tLett) in with.enumerate() where tLett == sLett {
          let curLen = mat[i][j] + 1
          mat[i + 1][j + 1] = curLen
          if curLen > len {
            len = curLen
            end = i
          }
        }
      }
      return self[advance(self.startIndex, (end + 1) - len)...advance(self.startIndex, end)]
  }
}

extension Sliceable where Generator.Element : Equatable, SubSlice.Generator.Element == Generator.Element {
  func contains<
    C: CollectionType where
    C.Generator.Element == Generator.Element,
    Index.Distance == C.Index.Distance
    > (col: C) -> Bool {
      return lazy(self.startIndex...advance(self.startIndex, self.count - col.count))
        .contains { self[$0..<advance($0, col.count)].elementsEqual(col) }
  }
}