Re: [閒聊] 每日LeetCode

看板Marginalman作者Rushia (みけねこ的鼻屎)時間1年前 (2023/03/18 13:44)推噓3(3推 0噓 3→)

留言6則, 5人參與討論串265/719 (看更多)

1472. Design Browser History 設計出瀏覽器的歷史記錄功能，包含： 1.BrowserHistory(string homepage) 初始化瀏覽器類別。 2.void visit(string url) 訪問url位置，並清空所有下一頁。 3.string back(int steps) 回到歷史記錄的上一頁並返回當前頁面，如果頁數不夠則返回最底頁。 4.string forward(int steps) 回到歷史記錄的下一頁並返回當前頁面，如果頁數不夠則返回最底頁。 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" 思路： 1.用一個雙向鏈結串列表示歷史記錄，back和forward就只是移動指標，visit就new一個新的node並把右邊的連結打斷即可。 Java Code： ------------------------------------- class BrowserHistory { private Node curr; public BrowserHistory(String homepage) { curr = new Node(homepage); } public void visit(String url) { Node node = new Node(url); curr.next = node; node.prev = curr; curr = curr.next; } public String back(int steps) { if (curr.prev == null) { return curr.val; } for (int i = 0; i < steps && curr.prev != null; i++) { curr = curr.prev; } return curr.val; } public String forward(int steps) { if (curr.next == null) { return curr.val; } for (int i = 0; i < steps && curr.next != null; i++) { curr = curr.next; } return curr.val; } } class Node { Node next; Node prev; String val; public Node(){}; public Node(String val) { this.val = val; } } ------------------------------------- -- https://i.imgur.com/PIoxddO.jpg