How hard is LeetCode 513. Find Bottom Left Tree Value?

LeetCode 513. Find Bottom Left Tree Value is rated Medium on LeetCode.

What is the time complexity of LeetCode 513. Find Bottom Left Tree Value?

The Python solution on this page runs in O(V+E).

What is the space complexity of LeetCode 513. Find Bottom Left Tree Value?

The Python solution on this page uses O(V) auxiliary space.

What topics does LeetCode 513. Find Bottom Left Tree Value cover?

LeetCode 513. Find Bottom Left Tree Value is tagged Tree, Depth-First Search, Breadth-First Search and Binary Tree on LeetCode.

Find Bottom Left Tree Value — LeetCode 513 Python Solution

MediumTreeDepth-First SearchBreadth-First SearchBinary Tree

Problem: #513
Pattern: Tree Traversal
Reading time: 3 min
Source: leetcode.com

The problem

Given the root of a binary tree, return the leftmost value in the last row of the tree.

Example

Input: root = [2,1,3]
Output: 1

Python solution

Python

# 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 findBottomLeftValue(self, root: Optional[TreeNode]) -> int:
        q = deque([root])
        ans = 0
        while q:
            ans = q[0].val
            for _ in range(len(q)):
                node = q.popleft()
                if node.left:
                    q.append(node.left)
                if node.right:
                    q.append(node.right)
        return ans

Complexity

Measure	Complexity
Time	O(V+E)
Space	O(V) auxiliary

Pattern: Tree Traversal

Choose the order — preorder, inorder, postorder, level — and the problem solves itself. LeetCode 513. Find Bottom Left Tree Value is filed here because LeetCode tags it Tree and Binary Tree, which is the vocabulary this hub collects.

The tree traversal guide has the Python template for the pattern and the 225 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 513. Find Bottom Left Tree Value?: LeetCode 513. Find Bottom Left Tree Value is rated Medium on LeetCode.
What is the time complexity of LeetCode 513. Find Bottom Left Tree Value?: The Python solution on this page runs in O(V+E).
What is the space complexity of LeetCode 513. Find Bottom Left Tree Value?: The Python solution on this page uses O(V) auxiliary space.
What topics does LeetCode 513. Find Bottom Left Tree Value cover?: LeetCode 513. Find Bottom Left Tree Value is tagged Tree, Depth-First Search, Breadth-First Search and Binary Tree on LeetCode.