Create 0232-implement-queue-using-stacks.kt

a93a · web-flow · commit d62715d3ad5d · 2024-01-29T12:00:12.000+01:00
diff --git a/kotlin/0232-implement-queue-using-stacks.kt b/kotlin/0232-implement-queue-using-stacks.kt
@@ -0,0 +1,28 @@
+class MyQueue() {
+    var s1 = LinkedList<Int>()
+    var s2 = LinkedList<Int>()
+
+    fun push(x: Int) {
+        s1.addLast(x)
+    }
+
+    fun pop(): Int {
+        if (s2.isEmpty())
+            refill()
+        return s2.removeLast() ?: -1
+    }
+
+    fun peek(): Int {
+        if (s2.isEmpty())
+            refill()
+        return s2.peekLast() ?: -1
+    }
+
+    fun empty() = maxOf(s1.size, s2.size) == 0
+
+    private fun refill() {
+        while (s1.isNotEmpty())
+            s2.addLast(s1.removeLast())
+    }
+
+}
