struct Solution {}
impl Solution {
    pub fn validate_stack_sequences(pushed: Vec<i32>, popped: Vec<i32>) -> bool {
        let mut stack: Vec<i32> = vec![];

        let mut i = 0;
        let mut j = 0;

        loop {
            // If the top is to be popped, pop it
            if let Some(&top) = stack.last() {
                if j < popped.len() && top == popped[j] {
                    stack.pop();
                    j += 1;
                    continue;
                }
            }

            // If I have an element that can be pushed, push it
            if i < pushed.len() {
                stack.push(pushed[i]);
                i += 1;
                continue;
            }

            // If I can't pop nor push, it's done or screwed up
            break;
        }

        // If it's correct simulation, stack must be empty
        stack.is_empty()
    }
}

fn main() {}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn success() {
        assert!(Solution::validate_stack_sequences(
            vec![1, 2, 3, 4, 5],
            vec![4, 5, 3, 2, 1]
        ));
    }

    #[test]
    fn fail() {
        assert!(!Solution::validate_stack_sequences(
            vec![1, 2, 3, 4, 5],
            vec![4, 3, 5, 1, 2]
        ));
    }
}