Merge pull request #162 from khanhtranngoccva/master

feat: Added JS implementation of a Python counter

Author: akshitagupta15june

Array/LongStrWithoutRepeat.js renamed to Array/LongStrWithoutRepeat.js

@@ -0,0 +1,52 @@
+/**
+ * Counts items in a string, an array, or an iterable in a similar way as in Python.
+ *
+ * @class
+ */
+class CollectionCounter extends Map {
+    /**
+     * Create a counter object that counts items of arbitrary types in a string, an array, or an iterable
+     * in a manner that is similar to Python. Implementation uses the JS map data structure.
+     *
+     * @param iterable {string|any[]|Generator} An arbitrary iterable collection, be it an
+     * array, a string or a generator. Requires the {@link Symbol.iterator} property.
+     * @returns {CollectionCounter} The counter that tracks how many items are there.
+     */
+    constructor(iterable) {
+        if (!new.target) {
+            return new CollectionCounter(iterable);
+        }
+        super();
+        for (let item of iterable) {
+            super.set(item, this.get(item) + 1);
+        }
+    }
+
+    /**
+     * Get how many items are there in the collection.
+     *
+     * @param item The key to get the count of the item.
+     * @returns {number} 0 if the item is not present in the original iterable value.
+     */
+    get(item) {
+        const quantity = super.get(item);
+        if (quantity === undefined) {
+            return 0;
+        } else {
+            return quantity;
+        }
+    }
+
+    set() {
+        throw new Error("This counter is not supposed to be modified!");
+    }
+}
+
+const stringCounter = new CollectionCounter("zebra duck elephant kitten bat");
+const arrayCounter = new CollectionCounter([
+    1, 4, 2, 5, 7, 4, 2, 6, 3, 1,
+    5, 3, 6, 2, 7, 9, 7, 8, 6, 8,
+    5, 3, 1, 6, 4, 8, 4, 4, 7, 0
+]);
+console.log(stringCounter);
+console.log(arrayCounter);