Binary Tree General — Reasoning Check

Distinguish path contracts, traversal information, and target identity on new trees.

Get every question correct to pass this checkpoint. You can review feedback, revise your answers, and submit again.

1. A tree has root -20, left leaf 2, and right child 5 whose leaf children are 4 and 9. What is its maximum nonempty simple-path sum? Enter one integer.

2. Path Sum searches for target 3 in a tree with root 7 and leaf children -4 and 2. A proposed optimization stops whenever the running sum exceeds 3. What happens?

Select one answer.

It finds both leaves because only the final node value matters It is correct if the left subtree is searched before the right subtree It correctly rejects both branches because all descendants increase the sum It misses the valid path 7→-4 because a later negative value can reduce the sum

3. Reconstruct the tree from preorder [11,5,2,8,17,13] and inorder [2,5,8,11,13,17]. What value is the left child of the root’s right child?

4. Tree A has root 2 with leaf children 1 and 3. Tree B is the right-child chain 1→2→3. A SameTree implementation compares only the two inorder value lists. What defect does this input expose?

Select one answer.

The implementation wrongly rejects two equal trees because roots differ The trees are equal because they contain the same multiset of values It accepts different shapes because both inorder lists are [1,2,3] Inorder cannot visit a node with only one child

5. Root R has children A and B. A is a leaf with value 4. B has leaf children P (value 4) and Q (value 6). For target pointers P and Q, which LCA result satisfies the contract?

Select one answer.

A, because its value equals P’s value A newly allocated node with B’s value R, because a value 4 occurs in both child subtrees The existing node B

6. For SumNumbers, root digit 0 has left child 3 and right leaf 2. Node 3 has leaf children 4 and 5. What sum is returned?

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