Create 0394-decode-string.kt

Author: a93a

Diff for: kotlin/0394-decode-string.kt

@@ -0,0 +1,25 @@
+class Solution {
+    fun decodeString(s: String): String {
+        val stack = LinkedList<String>()
+
+        for (c in s) {
+            if (c != ']') {
+                stack.addLast(c.toString())
+            } else {
+                val sb = StringBuilder()
+                while (stack.isNotEmpty() && stack.peekLast() != "[")
+                    sb.insert(0, stack.removeLast())
+                stack.removeLast()
+
+                val k = StringBuilder()
+                while (stack.isNotEmpty() && stack.peekLast().all { char -> char.isDigit() })
+                    k.insert(0, stack.removeLast())
+
+                val times = k.toString().toInt()
+                stack.addLast(sb.toString().repeat(times))
+            }
+        }
+
+        return stack.joinToString("")
+    }
+}