Duplicate numbers are not allowed in the answer set

app/src/androidTest/java/com/example/quickmax/MainActivityTest.kt

@@ -22,11 +22,11 @@ import org.junit.Before
 class MainActivityTest {
     @get:Rule
     val testRule = ActivityTestRule<MainActivity>(MainActivity::class.java)
-    private lateinit var radioGroup: RadioGroup
+//    private lateinit var radioGroup: RadioGroup
 
     @Before
     fun init() {
-        radioGroup = testRule.activity.radio_group
+//        radioGroup = testRule.activity.radio_group
     }
 
     @Test

app/src/main/java/com/example/quickmax/AnswerSet.kt

@@ -3,21 +3,26 @@ package com.example.quickmax
 
 class AnswerSet(numDigits: Int): Iterable<Answer> {
 
-    private val buttonIds =
-        listOf(R.id.btn_left_top, R.id.btn_right_top, R.id.btn_left_bottom, R.id.btn_right_bottom)
-    private val numOptions = 4
-
-    val numbers: MutableList<Answer> =
-        MutableList(numOptions) { i -> Answer(buttonIds[i], generateRandom(numDigits)) }
+    val buttonIds = listOf(R.id.btn_left_top, R.id.btn_right_top, R.id.btn_left_bottom, R.id.btn_right_bottom)
+    private val numAnswers = 4
+    private lateinit var correctAnswer: Answer
 
+    val answers: MutableList<Answer> = mutableListOf()
     init {
-        val correctAnswer = findSecondMax(numbers.map { n -> n.value })
-        numbers.forEach { n ->
-            n.correct = n.value == correctAnswer
+        val randomNumbers = generateNRandomNumbers(numDigits, numAnswers)
+        for (i in 0 until numAnswers)
+            answers.add(Answer(buttonIds[i], randomNumbers.elementAt(i)))
+
+        val correctAnswerNum = findSecondMax(answers.map { answer -> answer.value })
+        answers.forEach { n ->
+            n.correct = n.value == correctAnswerNum
+            if (n.correct)
+                correctAnswer = n
         }
     }
 
     override fun iterator(): Iterator<Answer> {
-        return numbers.iterator()
+        return answers.iterator()
     }
+
 }
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app/src/main/java/com/example/quickmax/Calculator.kt

@@ -8,6 +8,14 @@ fun generateRandom(numDigits: Int): Int {
     return (start..end).shuffled().first()
 }
 
+fun generateNRandomNumbers(numDigits: Int, n: Int): Set<Int> {
+    val randomNumbers = setOf<Int>()
+    while (randomNumbers.size < n) {
+        randomNumbers.plus(generateRandom(numDigits))
+    }
+    return randomNumbers
+}
+
 fun findSecondMax(numbers: List<Int>): Int {
     var firstMax = 0
     var secondMax = 0

app/src/test/java/com/example/quickmax/AnswerSetTest.kt

@@ -12,13 +12,13 @@ class AnswerSetTest {
 
     @Test
     fun test_constructor() {
-        assertEquals(numOptions, numberSet.numbers.size)
-        numberSet.numbers.forEach { n -> n in (100..999) }
+        assertEquals(numOptions, numberSet.answers.size)
+        numberSet.answers.forEach { n -> n in (100..999) }
     }
 
     @Test
     fun isCorrect() {
-        val secondMax = findSecondMax(numberSet.numbers)
+        val secondMax = findSecondMax(numberSet.answers)
         assertTrue(numberSet.isCorrect(secondMax))
     }
 }
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