add 2619, 2620, 2623, 2626

Author: rustykitty

2619-array-prototype-last.js

@@ -0,0 +1,20 @@
+/*
+2619. Array Prototype Last
+
+Submitted: January 14, 2025
+
+Runtime: 47 ms (beats 75.77%)
+Memory: 48.37 MB (beats 88.52%)
+*/
+
+/**
+ * @return {null|boolean|number|string|Array|Object}
+ */
+Array.prototype.last = function() {
+    return this.length == 0 ? -1 : this[this.length - 1];
+}
+
+/**
+ * const arr = [1, 2, 3];
+ * arr.last(); // 3
+ */

2620-counter.js

@@ -0,0 +1,25 @@
+/*
+2620. Counter
+
+Submitted: January 14, 2025
+
+Runtime: 36 ms (beats 99.12%)
+Memory: 48.94% (beats 48.41%)
+*/
+
+/**
+ * @param {number} n
+ * @return {Function} counter
+ */
+var createCounter = function(n) {
+    return function() {
+        return n++;
+    };
+};
+
+/** 
+ * const counter = createCounter(10)
+ * counter() // 10
+ * counter() // 11
+ * counter() // 12
+ */

2623-memoize.js

@@ -0,0 +1,32 @@
+/*
+2623. Memoize
+
+Submitted: January 14, 2025
+
+Runtime: 357 ms (beats 10.01%)
+Memory: 87.11 MB (beats 68.94%)
+*/
+
+/**
+ * @param {Function} fn
+ * @return {Function}
+ */
+function memoize(fn) {
+    let cache = {}
+    return function(...args) {
+        if (args in cache) return cache[args];
+        else return (cache[args] = fn(...args));
+    }
+}
+
+
+/** 
+ * let callCount = 0;
+ * const memoizedFn = memoize(function (a, b) {
+ *	 callCount += 1;
+ *   return a + b;
+ * })
+ * memoizedFn(2, 3) // 5
+ * memoizedFn(2, 3) // 5
+ * console.log(callCount) // 1 
+ */

2626-array-reduce-transformation.js

@@ -0,0 +1,21 @@
+/*
+2626. Array Reduce Transformation
+
+Submitted: January 14, 2025
+
+Runtime: 48 ms (beats 86.37%)
+Memory: 50.66 MB (beats 8.79%)
+*/
+
+/**
+ * @param {number[]} nums
+ * @param {Function} fn
+ * @param {number} init
+ * @return {number}
+ */
+var reduce = function(nums, fn, init) {
+    for (const n of nums) {
+        init = fn(init, n);
+    }
+    return init;
+};