LeetCode199 二叉树的右视图（bfs）

LeetCode199 二叉树的右视图

bfs记录每层最后一位被遍历的节点值

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def rightSideView(self, root: Optional[TreeNode]) -> List[int]:

        ans, depth, queue = {}, -1, [(root, 0)]

        while queue:

            cur_root, cur_depth = queue.pop(0)
            if cur_root:
                depth = max(depth, cur_depth)
                ans[cur_depth] = cur_root.val

                queue.append((cur_root.left, cur_depth + 1))
                queue.append((cur_root.right, cur_depth + 1))

        return [ans[i] for i in range(depth + 1)]