LeetCode: Queue from 2-Stacks in Rust

main.rs

struct MyQueue {
    queue: Vec<i32>,
    stack: Vec<i32>,
}

/**
 * `&self` means the method takes an immutable reference.
 * If you need a mutable reference, change it to `&mut self` instead.
 */
impl MyQueue {
    fn new() -> Self {
        Self {
            queue: Vec::new(),
            stack: Vec::new(),
        }
    }

    fn push(&mut self, x: i32) {
        self.stack.push(x);
    }

    fn pop(&mut self) -> i32 {
        if let Some(x) = self.queue.pop() {
            return x;
        }
        self.rebalance();
        self.queue.pop().unwrap()
    }

    fn peek(&mut self) -> i32 {
        if let Some(x) = self.queue.last() {
            return *x;
        }
        self.rebalance();
        *self.queue.last().unwrap()
    }

    fn empty(&self) -> bool {
        self.queue.is_empty() && self.stack.is_empty()
    }

    fn rebalance(&mut self) {
        while let Some(x) = self.stack.pop() {
            self.queue.push(x);
        }
    }
}


fn main() { }