Add solution #1472

Author: JoshCrozier

README.md

@@ -85,6 +85,7 @@
 1332|[Remove Palindromic Subsequences](./1332-remove-palindromic-subsequences.js)|Easy|
 1333|[Filter Restaurants by Vegan-Friendly, Price and Distance](./1333-filter-restaurants-by-vegan-friendly-price-and-distance.js)|Medium|
 1360|[Number of Days Between Two Dates](./1360-number-of-days-between-two-dates.js)|Easy|
+1472|[Design Browser History](./1472-design-browser-history.js)|Medium|
 1598|[Crawler Log Folder](./1598-crawler-log-folder.js)|Easy|
 1880|[Check if Word Equals Summation of Two Words](./1880-check-if-word-equals-summation-of-two-words.js)|Easy|
 

solutions/1472-design-browser-history.js

@@ -0,0 +1,59 @@
+/**
+ * 1472. Design Browser History
+ * https://leetcode.com/problems/design-browser-history/
+ * Difficulty: Medium
+ *
+ * You have a browser of one tab where you start on the homepage and you
+ * can visit another url, get back in the history number of steps or move
+ * forward in the history number of steps.
+ *
+ * Implement the BrowserHistory class:
+ *
+ * - `BrowserHistory(string homepage)` Initializes the object with the
+ *   homepage of the browser.
+ * - `void visit(string url)` Visits url from the current page. It clears
+ *   up all the forward history.
+ * - `string back(int steps)` Move steps back in history. If you can only
+ *   return x steps in the history and steps > x, you will return only x
+ *   steps. Return the current url after moving back in history at most steps.
+ * - `string forward(int steps)` Move steps forward in history. If you can
+ *   only forward x steps in the history and steps > x, you will forward only
+ *   x steps. Return the current url after forwarding in history at most steps.
+ */
+
+/**
+ * @param {string} homepage
+ */
+var BrowserHistory = function(homepage) {
+  this.history = [];
+  this.cursor = -1;
+  this.visit(homepage);
+};
+
+/**
+ * @param {string} url
+ * @return {void}
+ */
+BrowserHistory.prototype.visit = function(url) {
+  this.history.splice(this.cursor + 1, this.history.length);
+  this.history.push(url);
+  this.cursor++;
+};
+
+/**
+ * @param {number} steps
+ * @return {string}
+ */
+BrowserHistory.prototype.back = function(steps) {
+  this.cursor = Math.max(0, this.cursor - steps);
+  return this.history[this.cursor];
+};
+
+/**
+ * @param {number} steps
+ * @return {string}
+ */
+BrowserHistory.prototype.forward = function(steps) {
+  this.cursor = Math.min(this.cursor + steps, this.history.length - 1);
+  return this.history[this.cursor];
+};