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Heap for the Top, Tree for Any Key

Push 1 onto a heap and find 4 in a search tree to feel single-path repair and comparison-guided search.

The Runtime Theory Team05 stages

trace / request.md

NAME THEGUARANTEESTORE THEHEAP FLATREPAIR ONE PATHKEEP TREESBALANCEDPICK PER QUERY

readyA search tree orders everything left to right so comparisons steer to any key. A heap keeps only parent-outranks-child, enough to expose the extreme at the root.

Insert 1 into heap [3, 5, 4] and watch it bubble to the root, then steer down a tree to 4 in two comparisons.

For the worked walkthrough, continue to the topic article and execution trace.

Stage-by-stage execution walkthrough

This request flow decomposes Heap for the Top, Tree for Any Key into 5 sequential stages so you can trace where latency accumulates, which state transitions are irreversible, and where production failure modes occur.

Stage 1: Name the guarantee

A search tree orders everything left to right so comparisons steer to any key. A heap keeps only parent-outranks-child, enough to expose the extreme at the root. During this transition, the runtime enforces strict state invariants before handing control to the next stage: inputs are validated at the boundary, state mutations are ordered deterministically, and latency/resource costs are bounded so downstream consumers never observe a torn or partially initialized state.

Stage 2: Store the heap flat

A complete heap packs into an array with children of index i at 2i plus 1 and 2i plus 2. No pointers; shape stays complete by construction. During this transition, the runtime enforces strict state invariants before handing control to the next stage: inputs are validated at the boundary, state mutations are ordered deterministically, and latency/resource costs are bounded so downstream consumers never observe a torn or partially initialized state.

Stage 3: Repair one path

Appended 1 sifts up past 5 then 3 to the root; a removed top would sift the last element down. Each repair swaps along a single logarithmic path. During this transition, the runtime enforces strict state invariants before handing control to the next stage: inputs are validated at the boundary, state mutations are ordered deterministically, and latency/resource costs are bounded so downstream consumers never observe a torn or partially initialized state.

Stage 4: Keep trees balanced

Unbalanced trees fed sorted keys chain into linear height. Rotations hold balanced height logarithmic so lookup and ordered traversal stay fast. During this transition, the runtime enforces strict state invariants before handing control to the next stage: inputs are validated at the boundary, state mutations are ordered deterministically, and latency/resource costs are bounded so downstream consumers never observe a torn or partially initialized state.

Stage 5: Pick per query

Earliest-deadline schedulers take the heap; membership, predecessor, and range queries take the tree. Arbitrary heap lookup still scans everything. During this transition, the runtime enforces strict state invariants before handing control to the next stage: inputs are validated at the boundary, state mutations are ordered deterministically, and latency/resource costs are bounded so downstream consumers never observe a torn or partially initialized state.

Production invariants and failure modes

Heaps serve top-only access from a flat array; search trees serve ordered queries through balanced comparison paths. When debugging or capacity-planning this flow in production, instrument each stage boundary separately (measuring both p50 median and p99.9 tail latency), verify what happens when an intermediate stage times out or drops packets, and ensure retry or fallback paths preserve end-to-end idempotency.

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