add 341

Author: Ashwagandha-coder

contest/src/main/java/com/github/contest/design/DesignAlternativeSolution.kt

@@ -0,0 +1,29 @@
+package com.github.contest.design
+
+/**
+ * 341. Flatten Nested List Iterator
+ * Alternative Solution
+ */
+
+class NestedIteratorAlternativeSolution(nestedList: List<NestedInteger>) {
+
+    private val stack = ArrayDeque<NestedInteger>().apply {
+        nestedList.reversed().forEach { addFirst(it) }
+    }
+
+    fun next(): Int {
+        if (!hasNext()) throw NoSuchElementException()
+        return stack.removeFirst().getInteger()!!
+    }
+
+    fun hasNext(): Boolean {
+        while (stack.isNotEmpty()) {
+            val top = stack.first()
+            if (top.isInteger()) {
+                return true
+            }
+            stack.removeFirst().getList()?.reversed()?.forEach { stack.addFirst(it) }
+        }
+        return false
+    }
+}

contest/src/main/java/com/github/contest/design/DesignLeetcode.kt

@@ -252,6 +252,9 @@ class CombinationIterator(characters: String, combinationLength: Int) {
  */
 
 class NestedInteger {
+
+    fun isInteger() = true
+
     fun getInteger(): Int? {
         return null
     }