MainActivity.kt

class MainActivity : AppCompatActivity() , ProblemItemListener {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)
        setTitle(R.string.app_name)

        val problemList = binding.problemsList
        val mode = binding.mode
        mode.text = getString(R.string.app_title)
        val list = listOf(
            Problem(1, "Two Sum", false),
            Problem(2, "Maximum Sub Array", false),
            Problem(3, "Reverse Words", false),
            Problem(4, "Min Stack", false),
            Problem(5, "Edit Distance", false),
            Problem(6, "Reverse Integer", false),
            Problem(7, "Count and Say", false),
            Problem(8, "Trapping Rain Water", false),
            Problem(9, "Wildcard Matching", false),
        )
        problemList.adapter = ProblemsAdapter(list,this)
        problemList.layoutManager = LinearLayoutManager(this,LinearLayoutManager.HORIZONTAL,false)
    }

    override fun onItemClicked(item: Problem) {
        Toast.makeText(this, "${item.problemNumber} : ${item.problemName}", Toast.LENGTH_LONG).show()
    }
}