Tonight's goal is one clean Month 2 interview rehearsal: three timed problems, spoken approach first, no solution text during the timer, and a score you compare to Day 30.
Tonight's protocol
0:00-0:05: answer the warm-up MCQs below. Do not open notes. Solving starts when this five-minute box ends.
0:05: start one strict 60-minute timer. Use the same Day 30 conditions from the mock-day protocol: timer first, talk first, code second.
0:05-0:25: solve the Trees problem. Spend the first 2 minutes saying the pattern, brute force, better approach, and time/space out loud.
0:25-0:45: solve the Heap problem with the same spoken checkpoint before typing. If stuck after 14 minutes in any box, look only at the pattern name in the menu.
0:45-1:05: solve the Graphs problem with the same spoken checkpoint. Stop when the timer ends; do not steal time from the score.
After the timer: score 1 point for an accepted solution inside its box, 0.5 for the right invariant with unfinished code, and 0 for a wrong direction. Compare today’s percentage with Day 30; that comparison is the progress measure.
The problem menu
Three problems only. For each one, explain aloud before coding, then attempt without solution text.
“The answer for a node is a function of its children's answers; trust the recursion on subtrees and only decide what happens at this node.”
2. Diameter DFS should return what?
“Compute height recursively and carry the real answer up alongside it — one traversal answers both questions.”
3. In Kth Largest, when the heap grows past k, what leaves?
“A heap hands you the best remaining element in O(log n) per update; keep a min-heap of size k to hold the k largest.”
4. What do two median heaps expose?
“A max-heap of the lower half and a min-heap of the upper half, kept balanced, put the median at the tops.”
5. Fresh land in a grid starts what?
“DFS floods everything reachable in one component; count how many times you must start a new flood. The grid itself is the adjacency list — mark visited in place.”
6. Which pair fits topological sort plus Dijkstra?
“A dependency order exists iff the directed graph has no cycle — detect it with three-color DFS or Kahn's in-degree peeling.” Also: “Dijkstra is BFS with a priority queue: always settle the closest unsettled node, because no cheaper path to it can appear later.”
Self-check gate
Pass bar
Pass tonight if you score at least 2 out of 3 and you said the approach plus complexity before coding all three problems.
If you score below 2, or if any problem started with silent coding, write one mistake line for each failed problem and add those problems to the next revision day. Use the format WA: <missed invariant or implementation bug>.