02-design-circular-queue.rs

struct MyCircularQueue {
    front: usize,
    end: usize,
    arr: Vec<i32>,
    size: usize,
}

/**
 * `&self` means the method takes an immutable reference.
 * If you need a mutable reference, change it to `&mut self` instead.
 */
impl MyCircularQueue {
    fn new(k: i32) -> Self {
        Self {
            arr: vec![0; k as usize],
            front: 0,
            end: 0,
            size: 0,
        }
    }

    fn en_queue(&mut self, value: i32) -> bool {
        if self.is_full() {
            return false;
        }
        self.size += 1;
        self.arr[self.end] = value;
        self.end = (self.end + 1) % self.arr.len();
        true
    }

    fn de_queue(&mut self) -> bool {
        if self.is_empty() {
            return false;
        }
        self.size -= 1;
        self.front = (self.front + 1) % self.arr.len();
        true
    }

    fn front(&self) -> i32 {
        if self.is_empty() {
            return -1;
        }
        self.arr[self.front]
    }

    fn rear(&self) -> i32 {
        if self.is_empty() {
            return -1;
        }
        self.arr[(self.end + self.arr.len() - 1) % self.arr.len()]
    }

    fn is_empty(&self) -> bool {
        self.size == 0
    }

    fn is_full(&self) -> bool {
        self.size == self.arr.len()
    }
}

/**
 * Your MyCircularQueue object will be instantiated and called as such:
 * let obj = MyCircularQueue::new(k);
 * let ret_1: bool = obj.en_queue(value);
 * let ret_2: bool = obj.de_queue();
 * let ret_3: i32 = obj.front();
 * let ret_4: i32 = obj.rear();
 * let ret_5: bool = obj.is_empty();
 * let ret_6: bool = obj.is_full();
 */