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110.balanced-binary-tree.rs
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110.balanced-binary-tree.rs
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/*
* @lc app=leetcode id=110 lang=rust
*
* [110] Balanced Binary Tree
*/
// @lc code=start
// 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;
use std::cmp;
impl Solution {
pub fn is_balanced(root: Option<Rc<RefCell<TreeNode>>>) -> bool {
fn helper(root: Option<Rc<RefCell<TreeNode>>>) -> (bool, i32) {
if let Some(rc_node) = root {
let tree_node = rc_node.borrow();
let (is_left_balanced, left_height) = helper(tree_node.left.clone());
let (is_right_balanced, right_height) = helper(tree_node.right.clone());
if is_left_balanced && is_right_balanced && (left_height - right_height).abs() <= 1 {
(true, cmp::max(left_height, right_height) + 1)
} else {
(false, 0)
}
} else {
(true, 0)
}
}
let (ans, _) = helper(root);
ans
}
}
// @lc code=end