题解 | #求二叉树的层序遍历# | Rust

/**
 * #[derive(PartialEq, Eq, Debug, Clone)]
 * pub struct TreeNode {
 *     pub val: i32,
 *     pub left: Option<Box<TreeNode>>,
 *     pub right: Option<Box<TreeNode>>,
 * }
 *
 * impl TreeNode {
 *     #[inline]
 *     fn new(val: i32) -> Self {
 *         TreeNode {
 *             val: val,
 *             left: None,
 *             right: None,
 *         }
 *     }
 * }
 */
struct Solution{

}

impl Solution {
    fn new() -> Self {
        Solution{}
    }

    /**
    * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
    *
    * 
        * @param root TreeNode类 
        * @return int整型二维数组
    */
    pub fn levelOrder(&self, root: Option<Box<TreeNode>>) -> Vec<Vec<i32>> {
        let mut ans : Vec<Vec<i32>> = Vec::new();
        if let Some(root) = root {
            let mut queue : VecDeque<Box<TreeNode>> = VecDeque::new();
            queue.push_back(root);
            while !queue.is_empty() {
                let mut n = queue.len();
                let mut item : Vec<i32> = Vec::new();
                for i in 0..n {
                    if let Some(node) = queue.pop_front() {
                        item.push(node.val);
                        if let Some(l) = node.left {
                            queue.push_back(l);
                        }
                        if let Some(r) = node.right {
                            queue.push_back(r);
                        }
                    }
                }
                ans.push(item);
            }
        }
        return ans;
    }
}