RESEARCH BLOG · ALGORITHM BY ALGORITHM

A rigorous reading path through every algorithm in the current public Python release. Each entry states the mathematical problem, the operative idea, the procedure, the certificate, the computational limit and the exact source file.

Research Blog & Public Algorithm Atlas

IMPLEMENTED_LOCAL_TESTEDGraph optimization

Dijkstra shortest path

Permanently settle the smallest tentative distance; nonnegative weights ensure that label can never improve later.

Complexity. O((|V|+|E|) log |V|)

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IMPLEMENTED_LOCAL_TESTEDGraph optimization

Connected components

One traversal from an unseen seed discovers exactly one component.

Complexity. O(|V|+|E|)

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IMPLEMENTED_LOCAL_TESTEDGraph optimization

Kruskal minimum spanning tree

Accept the lightest edge that joins different components.

Complexity. O(|E| log |E|)

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IMPLEMENTED_LOCAL_TESTEDExact combinatorial optimization

Hungarian assignment

Dual potentials expose zero reduced-cost augmenting assignments.

Complexity. O(n³) after padding

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IMPLEMENTED_LOCAL_TESTEDTSP bounds

TSP assignment relaxation

Every tour is a cycle cover, while a cycle cover may contain several cycles.

Complexity. O(n³)

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IMPLEMENTED_LOCAL_TESTEDTSP exact repair

Cycle contraction and patching

Enumerate cycle order and entry points while measuring bridge deltas exactly.

Complexity. Exponential in cycle count and entry choices

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IMPLEMENTED_LOCAL_TESTEDTSP exact repair

Cycle branch and bound

A lower bound on unfinished bridge cost prunes partial reconnections.

Complexity. Exponential in the worst case

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IMPLEMENTED_LOCAL_TESTEDInteger optimization

Binary branch and bound

LP relaxations bound subtrees; fractional variables split the search.

Complexity. Exponential in the worst case

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IMPLEMENTED_LOCAL_TESTEDInteger optimization

Branch and cut

Remove fractional LP points without removing integer-feasible solutions.

Complexity. Problem-dependent; exponential worst case

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IMPLEMENTED_LOCAL_TESTEDTSP exact

Held-Karp subset dynamic programming

The best partial tour is identified by visited subset and final vertex.

Complexity. O(2ⁿn²) time; O(2ⁿn) memory

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IMPLEMENTED_LOCAL_TESTEDTSP bounds

One-tree lower bound

Combine an MST excluding the depot with its two cheapest incident edges.

Complexity. O(n²) in the dense implementation

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IMPLEMENTED_LOCAL_TESTEDTSP heuristic

Nearest neighbour + 2-opt

Build greedily, then reverse segments that reduce two-edge cost.

Complexity. O(n³) in the simple implementation

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IMPLEMENTED_NOT_INDEPENDENTLY_VERIFIEDTruck + drone

Synchronization-state exact DP

A state needs the served mask and the common synchronization node.

Complexity. Exponential subset DP

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IMPLEMENTED_NOT_INDEPENDENTLY_VERIFIEDTruck + drone

Weighted-interval sortie DP

Take-or-skip recurrence over intervals ordered by rendezvous position.

Complexity. O(m²) with direct predecessor search

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IMPLEMENTED_NOT_INDEPENDENTLY_VERIFIEDTruck + drone

Fixed-tour sortie set-packing B&B

Represent candidate conflicts as binary set-packing inequalities.

Complexity. Exponential worst case

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IMPLEMENTED_NOT_INDEPENDENTLY_VERIFIEDTruck + drone

QUBO + classical annealing

Reward savings and penalize simultaneous conflicting sorties.

Complexity. Restarts × sweeps × candidate interactions

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IMPLEMENTED_NOT_INDEPENDENTLY_VERIFIEDTruck + drone

Best-improvement VND

Search several neighborhoods and accept the best exactly reevaluated move.

Complexity. Neighborhood- and round-dependent

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IMPLEMENTED_NOT_INDEPENDENTLY_VERIFIEDTruck + drone

Route-first, split-second

Decompose route construction from synchronization-aware sortie selection.

Complexity. Depends on route and split modes

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IMPLEMENTED_LOCAL_TESTEDDistributed experimentation

Deterministic Hadoop/Spark experiment planner

Stable case IDs and content hashes keep distribution separate from solver semantics.

Complexity. O(c log c) orchestration around solver cost

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