leetcode: Add 0622

src/leetcode/0622.design-circular-queue/Cargo.toml

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+[package]
+name = "lc-0622-design-circular-queue"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]

src/leetcode/0622.design-circular-queue/index.md

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+
+# 
+
+[问题描述](../problems/)

src/leetcode/0622.design-circular-queue/src/main.rs

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+// Copyright (c) 2024 Xu Shaohua <[email protected]>. All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#[derive(Debug, Clone)]
+pub struct MyCircularQueue {
+    size: usize,
+    // front 指向头部元素的上一个元素
+    front: usize,
+    // back 指向尾部元素的位置
+    back: usize,
+    data: Vec<i32>,
+}
+
+impl MyCircularQueue {
+    /// Initializes the object with the size of the queue to be k.
+    #[must_use]
+    #[inline]
+    pub fn new(k: i32) -> Self {
+        assert!(k > 0);
+        // 多分配一个元素, 这个位置用于标记队列是否已满, 它并不存储数据.
+        let size = k as usize + 1;
+        Self {
+            size,
+            front: 0,
+            back: 0,
+            data: vec![0; size],
+        }
+    }
+
+    /// Inserts an element into the circular queue.
+    ///
+    /// Return true if the operation is successful.
+    #[must_use]
+    pub fn en_queue(&mut self, value: i32) -> bool {
+        if self.is_full() {
+            false
+        } else {
+            self.back = (self.back + 1) % self.size;
+            self.data[self.back] = value;
+            true
+        }
+    }
+
+    #[must_use]
+    pub fn de_queue(&mut self) -> bool {
+        if self.is_empty() {
+            false
+        } else {
+            self.front = (self.front + 1) % self.size;
+            true
+        }
+    }
+
+    ///  Gets the front item from the queue.
+    ///
+    ///  If the queue is empty, return -1.
+    #[must_use]
+    pub fn front(&self) -> i32 {
+        if self.is_empty() {
+            -1
+        } else {
+            let index = (self.front + 1) % self.size;
+            self.data[index]
+        }
+    }
+
+    ///  Gets the last item from the queue.
+    ///
+    ///  If the queue is empty, return -1.
+    #[must_use]
+    pub fn rear(&self) -> i32 {
+        if self.is_empty() {
+            -1
+        } else {
+            self.data[self.back]
+        }
+    }
+
+    /// Checks whether the circular queue is empty or not.
+    #[must_use]
+    #[inline]
+    pub const fn is_empty(&self) -> bool {
+        // front 和 back 指向同一个元素, 表示队列为空.
+        self.front == self.back
+    }
+
+    /// Checks whether the circular queue is full or not.
+    #[must_use]
+    #[inline]
+    pub const fn is_full(&self) -> bool {
+        // back 与 front 之间留下一个元素, 表示队列已满.
+        (self.back + 1) % self.size == self.front
+    }
+}
+
+fn check_solution() {
+    let mut obj = MyCircularQueue::new(3);
+    assert!(obj.en_queue(1));
+    assert!(obj.en_queue(2));
+    assert!(obj.en_queue(3));
+    assert!(obj.de_queue());
+    assert_eq!(obj.front(), 2);
+    assert_eq!(obj.rear(), 3);
+    assert!(!obj.is_empty());
+    assert!(!obj.is_full());
+}
+
+fn main() {
+    check_solution();
+}
+
+#[cfg(test)]
+mod tests {
+    use super::check_solution;
+
+    #[test]
+    fn test_circular_queue() {
+        check_solution();
+    }
+}