Create 1352-product-of-the-last-k-numbers.js

Author: everthis

1352-product-of-the-last-k-numbers.js

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+/*
+ * @lc app=leetcode id=1352 lang=javascript
+ *
+ * [1352] Product of the Last K Numbers
+ */
+
+// @lc code=start
+
+const ProductOfNumbers = function() {
+  this.sum = [1]
+};
+
+/** 
+ * @param {number} num
+ * @return {void}
+ */
+ProductOfNumbers.prototype.add = function(num) {
+  if(num > 0) {
+    this.sum.push(this.sum[this.sum.length - 1] * num)
+  } else {
+    this.sum = [1]
+  }
+};
+
+/** 
+ * @param {number} k
+ * @return {number}
+ */
+ProductOfNumbers.prototype.getProduct = function(k) {
+  const len = this.sum.length
+  return k < len ? this.sum[len - 1] / this.sum[len - 1 - k] : 0
+};
+
+/** 
+ * Your ProductOfNumbers object will be instantiated and called as such:
+ * var obj = new ProductOfNumbers()
+ * obj.add(num)
+ * var param_2 = obj.getProduct(k)
+ */