binary tree right side view

• https://neetcode.io/problems/binary-tree-right-side-view/question

bfs solution (ez)

# 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]:
        if root == None: return []
 
        q = deque([root])
        res = []
 
        while q:
            qLen = len(q)
            last = None
            for i in range(qLen):
                cur = q.popleft()
                last = cur.val
                if cur.left: q.append(cur.left)
                if cur.right: q.append(cur.right)
            res.append(last)
        
        return res

dfs solution (woah)

class Solution:
    def rightSideView(self, root: Optional[TreeNode]) -> List[int]:
        if root is None: return []
        res = []
 
        def dfs(root, lvl):
            if root is None:
                return
            
            if len(res) == lvl:
                res.append(root.val)
 
            dfs(root.right, lvl + 1)
            dfs(root.left, lvl + 1)
 
        dfs(root, 0)
        return res

• the point is that you have to call the right side first!!