Package g1401_1500.s1472_design_browser_history

Class BrowserHistory

java.lang.Object
g1401_1500.s1472_design_browser_history.BrowserHistory
public class BrowserHistory extends java.lang.Object
1472 - Design Browser History.

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.

Example:

Input: [“BrowserHistory”,“visit”,“visit”,“visit”,“back”,“back”,“forward”,“visit”,“forward”,“back”,“back”] [[“leetcode.com”],[“google.com”],[“facebook.com”],[“youtube.com”],[1],[1],[1],[“linkedin.com”],[2],[2],[7]]

Output: [null,null,null,null,“facebook.com”,“google.com”,“facebook.com”,null,“linkedin.com”,“google.com”,“leetcode.com”]

Explanation:

BrowserHistory browserHistory = new BrowserHistory(“leetcode.com”);

browserHistory.visit(“google.com”); // You are in “leetcode.com”. Visit “google.com”

browserHistory.visit(“facebook.com”); // You are in “google.com”. Visit “facebook.com”

browserHistory.visit(“youtube.com”); // You are in “facebook.com”. Visit “youtube.com”

browserHistory.back(1); // You are in “youtube.com”, move back to “facebook.com” return “facebook.com”

browserHistory.back(1); // You are in “facebook.com”, move back to “google.com” return “google.com”

browserHistory.forward(1); // You are in “google.com”, move forward to “facebook.com” return “facebook.com”

browserHistory.visit(“linkedin.com”); // You are in “facebook.com”. Visit “linkedin.com”

browserHistory.forward(2); // You are in “linkedin.com”, you cannot move forward any steps.

browserHistory.back(2); // You are in “linkedin.com”, move back two steps to “facebook.com” then to “google.com”. return “google.com”

browserHistory.back(7); // You are in “google.com”, you can move back only one step to “leetcode.com”. return “leetcode.com”

Constraints:

  • 1 <= homepage.length <= 20
  • 1 <= url.length <= 20
  • 1 <= steps <= 100
  • homepage and url consist of ‘.’ or lower case English letters.
  • At most 5000 calls will be made to visit, back, and forward.

  • Constructor Summary

    Constructors
    Constructor
    Description
    BrowserHistory(java.lang.String homepage)
     

  • Method Summary

    Modifier and Type
    Method
    Description
    java.lang.String
    back(int steps)
     
    java.lang.String
    forward(int steps)
     
    void
    visit(java.lang.String url)
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • BrowserHistory

      public BrowserHistory(java.lang.String homepage)

  • Method Details

    • visit

      public void visit(java.lang.String url)

    • back

      public java.lang.String back(int steps)

    • forward

      public java.lang.String forward(int steps)