Programming & Data Structures

An in-order traversal of a binary search tree produces values in ascending order.. An in-order traversal visits the left subtree, then the node, then the right subtree, which for any binary search tree produces the values in ascending order: 20, 30, 40, 50, 60, 70.

A recursive function without a base case exhausts the call stack, causing a stack overflow error.. Each recursive call adds a new frame to the call stack, and without a base case the stack grows without limit until memory is exhausted, producing a stack overflow.

The queue starts with the front and rear pointers at index 6 and contains 0 elements. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.

• !People often forget that the rear pointer wraps around to the start of the array when it reaches the end, or they misunderstand how the modulo operator works in this context.
• !The insertion order or a left-node-right post-order arrangement are not correct.
• !A queue is often considered, but it would undo the oldest action first due to its first-in-first-out behavior.
• !Students often confuse stack overflow with other runtime errors such as division by zero or array out‑of‑bounds, but only unbounded recursion directly leads to stack overflow.
• !A value of 9 is wrong because a circular array of size 8 has no index beyond 7 and must wrap with modulo.

Answer each from memory — you'll see instantly whether you're right and why.

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