/**
 * [98] Validate Binary Search Tree
 */
pub struct Solution {}

use crate::util::tree::{TreeNode, to_tree};

// submission codes start here

// Definition for a binary tree node.
// #[derive(Debug, PartialEq, Eq)]
// pub struct TreeNode {
//   pub val: i32,
//   pub left: Option<Rc<RefCell<TreeNode>>>,
//   pub right: Option<Rc<RefCell<TreeNode>>>,
// }
//
// impl TreeNode {
//   #[inline]
//   pub fn new(val: i32) -> Self {
//     TreeNode {
//       val,
//       left: None,
//       right: None
//     }
//   }
// }
use std::rc::Rc;
use std::cell::RefCell;
impl Solution {
    fn inorder_iterate(node: &Rc<RefCell<TreeNode>>, array: &mut Vec<i32>) {
        if let Some(left) = node.borrow().left.as_ref() {
            Self::inorder_iterate(left, array);
        }   
        array.push(node.borrow().val);
        if let Some(right) = node.borrow().right.as_ref() {
            Self::inorder_iterate(right, array);
        }
    }

    pub fn is_valid_bst(root: Option<Rc<RefCell<TreeNode>>>) -> bool {
        let mut array = vec![];

        if let Some(root) = root {
            Self::inorder_iterate(&root, &mut array);
        }

        for i in 1..array.len() {
            if array[i - 1] >= array[i] {
                return false;
            }
        }

        true
    }
}

// submission codes end

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

    #[test]
    fn test_98() {
    }
}