How do you solve Root Equals Sum of Children on LeetCode?

Root Equals Sum of Children (LeetCode #2236) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(1) time complexity and O(1) space complexity. Key insight: The problem is very straightforward due to the fixed size of the tree.

What is the time complexity of Root Equals Sum of Children?

The optimal solution for Root Equals Sum of Children runs in O(1) time and uses O(1) space. The complexity remains O(1) as we are still performing a constant number of operations.

What is the brute force solution for Root Equals Sum of Children?

The brute force approach for Root Equals Sum of Children is Brute Force, with O(1) time complexity and O(1) space complexity. In this approach, we simply check if the value of the root node is equal to the sum of its left and right child nodes. It's straightforward and easy to implement since we only have three nodes. The optimal Optimal Solution approach improves this to O(1).

What algorithm or data structure is used to solve Root Equals Sum of Children?

Root Equals Sum of Children uses the following concepts: Tree, Binary Tree. The recommended patterns to study are: Tree, Binary Tree.

What are the interview tips for Root Equals Sum of Children?

Always clarify the structure of the input before diving into the solution. Think about edge cases, even if they seem trivial, like null children. Practice explaining your thought process as you write code.

What are common mistakes when solving Root Equals Sum of Children?

Forgetting to check if the left or right child is null before accessing their values. Confusing the sum operation or the comparison logic.

#2236

Root Equals Sum of Children

Easy

TreeBinary TreeTreeBinary Tree

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(1)	O(1)
Space	O(1)	O(1)

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Intuition

Time O(1)Space O(1)

Since we only need to check the values of three nodes, the optimal solution is essentially the same as the brute force approach. However, we can emphasize that this is the best we can do given the constraints.

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Algorithm

6 steps

1Step 1: Access the value of the root node.
2Step 2: Access the value of the left child node.
3Step 3: Access the value of the right child node.
4Step 4: Calculate the sum of the left and right child values.
5Step 5: Compare the root value with the calculated sum.
6Step 6: Return true if they are equal, otherwise return false.

solution.py8 lines

1class TreeNode:
2    def __init__(self, val=0, left=None, right=None):
3        self.val = val
4        self.left = left
5        self.right = right
6
7def checkTree(root):
8    return root.val == (root.left.val + root.right.val)

ℹ

Complexity note: The complexity remains O(1) as we are still performing a constant number of operations.

1The problem is very straightforward due to the fixed size of the tree.
2Understanding how to access child nodes is crucial for tree problems.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.