#1472

Design Browser History

pupil · 460 · lc medium +26 · 78.2% accepted · 4,131 likes · top 89%

Description

Design a BrowserHistory class that simulates single-tab browser navigation starting from a given homepage. Implement the following methods:

- BrowserHistory(string homepage) — initializes the browser at homepage.

- void visit(string url) — navigates to url, discarding all forward history.

- string back(int steps) — moves up to steps pages back, returning the current URL.

- string forward(int steps) — moves up to steps pages forward, returning the current URL.

Example 1:

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"]

Example 2:

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"

Code

class BrowserHistory:

    def __init__(self, homepage: str):
        

    def visit(self, url: str) -> None:
        

    def back(self, steps: int) -> str:
        

    def forward(self, steps: int) -> str:
        


# Your BrowserHistory object will be instantiated and called as such:
# obj = BrowserHistory(homepage)
# obj.visit(url)
# param_2 = obj.back(steps)
# param_3 = obj.forward(steps)

class BrowserHistory:

    def __init__(self, homepage: str):
        

    def visit(self, url: str) -> None:
        

    def back(self, steps: int) -> str:
        

    def forward(self, steps: int) -> str:
        


# Your BrowserHistory object will be instantiated and called as such:
# obj = BrowserHistory(homepage)
# obj.visit(url)
# param_2 = obj.back(steps)
# param_3 = obj.forward(steps)