20250226 finished.

src/problem/mod.rs

@@ -506,3 +506,5 @@ mod p1206_design_skiplist;
 mod p1656_design_an_ordered_stream;
 
 mod p2502_design_memory_allocator;
+
+mod p1472_design_browser_history;

src/problem/p1472_design_browser_history.rs

@@ -0,0 +1,87 @@
+/**
+ * [1472] Design Browser History
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+struct BrowserHistory {
+    history: Vec<String>,
+    pos: usize,
+}
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl BrowserHistory {
+    fn new(homepage: String) -> Self {
+        Self {
+            history: vec![homepage],
+            pos: 0,
+        }
+    }
+
+    fn visit(&mut self, url: String) {
+        // 删除前向的所有网站
+        for _ in self.pos + 1..self.history.len() {
+            self.history.pop();
+        }
+
+        self.history.push(url);
+        self.pos += 1;
+    }
+
+    fn back(&mut self, steps: i32) -> String {
+        let steps = steps as usize;
+        if steps > self.pos {
+            self.pos = 0;
+        } else {
+            self.pos -= steps;
+        }
+
+        self.history[self.pos].clone()
+    }
+
+    fn forward(&mut self, steps: i32) -> String {
+        let steps = steps as usize;
+        if steps + self.pos >= self.history.len() {
+            self.pos = self.history.len() - 1;
+        } else {
+            self.pos += steps;
+        }
+
+        self.history[self.pos].clone()
+    }
+}
+
+/**
+ * Your BrowserHistory object will be instantiated and called as such:
+ * let obj = BrowserHistory::new(homepage);
+ * obj.visit(url);
+ * let ret_2: String = obj.back(steps);
+ * let ret_3: String = obj.forward(steps);
+ */
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1472() {
+        let mut history = BrowserHistory::new("leetcode.com".to_owned());
+
+        history.visit("google.com".to_owned());
+        history.visit("facebook.com".to_owned());
+        history.visit("youtube.com".to_owned());
+        assert_eq!("facebook.com", history.back(1));
+        assert_eq!("google.com", history.back(1));
+        assert_eq!("facebook.com", history.forward(1));
+        history.visit("linkedin.com".to_owned());
+        assert_eq!("linkedin.com", history.forward(2));
+        assert_eq!("google.com", history.back(2));
+        assert_eq!("leetcode.com", history.back(7));
+    }
+}