Create counter-ii.ts

Author: kamyu104

TypeScript/counter-ii.ts

@@ -0,0 +1,30 @@
+// Time:  ctor:      O(1)
+//        increment: O(1)
+//        decrement: O(1)
+//        reset:     O(1)
+// Space: O(1)
+
+// design
+class Counter {
+    init: number;
+    curr: number;
+    constructor(init: number) {
+        this.curr = this.init = init;
+    }
+
+    increment() {
+        return ++this.curr;
+    }
+
+    decrement() {
+        return --this.curr;
+    }
+
+    reset() {
+        return this.curr = this.init;
+    }
+};
+
+function createCounter(init: number) {
+    return new Counter(init);
+};