Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsChoose a C++ assignment solver by matching it to the constraints you need to express—not by picking a library that sounds fastest. A plain one-to-one cost-minimization problem may fit a specialized linear assignment solver; capacities and supplies may fit minimum-cost flow; additional business rules may require MIP or CP-SAT. Then benchmark the candidates on representative production inputs and verify their results, numeric limits, and failure behavior.
Define the assignment problem before choosing a solver
A basic assignment problem selects worker-task pairs to minimize total cost. Each worker can receive at most one task, and a task cannot be assigned more than once. Depending on the formulation, some workers or tasks may remain unmatched; for example, a model with more workers than tasks can leave workers idle. See Google’s assignment overview and its C++ linear assignment example.
Write down the actual model before comparing APIs. Record the two sides of the assignment, which pairs are allowed, what each cost means and its numeric range, whether either side may remain unmatched, and any capacities, quotas, or other side constraints. These details determine whether a specialized assignment routine is enough or whether a broader model is needed.
- One-to-one rules: Can each participant receive at most one match, or can either side take several?
- Optional assignments: Is leaving a worker or task unmatched permitted, and what does that mean for the objective?
- Allowed pairs: Are all pairs possible, or is the input a sparse graph of eligible pairs?
- Costs and capacities: Are values integral or real-valued, what are their bounds, and are supplies or quotas involved?
- Business rules: Do logical conditions or other constraints go beyond assignment and flow structure?
Choose the solver family that fits the model
Linear sum assignment for the plain one-to-one case
A specialized linear sum assignment solver is a natural candidate when the model is a straightforward cost-matrix assignment. OR-Tools provides a C++ API with assignment-cost and right-mate access, and its examples check that the solver reports an optimal status before using the result. Google says this specialized tool can be faster than MIP or CP-SAT on the simple case; that is a qualitative selection signal, not a guarantee for every workload. Read the OR-Tools linear assignment documentation.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
Minimum-cost flow for graph, capacity, or supply structure
Assignment can also be expressed as a network-flow problem. As Google’s C++ optimization introduction puts it, “Assignment problems are actually a special case of network flow problems.” Minimum-cost flow is worth considering when the graph naturally captures eligible pairs, capacities, or supplies. OR-Tools provides a C++ SimpleMinCostFlow example, and its documentation says flow can often return some assignment solutions faster than MIP or CP-SAT. It remains less general than those broader modeling approaches. See the OR-Tools assignment-as-min-cost-flow example.
LEMON is another min-cost-flow option. Its CostScaling reference says edge capacities and costs should be non-negative integers. That is a constraint on the documented CostScaling implementation, not a rule to assume for every solver. The URL points to latest-SVN documentation, so verify the corresponding documentation for the release you intend to use.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
MIP or CP-SAT when assignment rules are not enough
If the model includes additional business or logical constraints that a specialized assignment or flow formulation cannot express cleanly, consider MIP or CP-SAT. Google recommends these for broader assignment problems and notes that the simpler assignment and flow tools handle only simple types of assignment problems. This is a statement about modeling range; it does not establish a universal speed ranking. The OR-Tools assignment overview describes the distinction.
Treat Hungarian as an implementation choice, not a performance guarantee
“Hungarian” or “Kuhn–Munkres” identifies an algorithm family, not a promise about the behavior of a particular C++ implementation. Google’s Hungarian reference describes its specific implementation as O(n4) and recommends using graph/linear_assignment.h instead because that implementation’s complexity is usually much smaller. The same reference warns that NaN input can leave outputs unchanged. These statements apply to the documented Google implementation; they do not characterize every Hungarian implementation. See the Google Hungarian C++ reference, last updated 2024-08-06 UTC.
Recommended Free Tools
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
Compare candidates on production-relevant criteria
Only compare candidates that can encode the required model. For those candidates, use the following criteria to create a practical shortlist:
| Criterion | What to check |
|---|---|
| Constraint fit | Whether the solver handles plain one-to-one assignments, flow capacities and supplies, or the broader logical and business constraints in the model. |
| Input shape | Whether production inputs are dense cost matrices or sparse allowed-pair graphs; whether the two sides are balanced; and whether unmatched participants are allowed. |
| Numeric contract | Supported cost and capacity types, integer scaling if business costs are real-valued, overflow bounds, and documented handling of forbidden pairs. LEMON CostScaling’s cited reference specifies non-negative integer costs and capacities; do not infer the same restriction for other solvers. |
| C++ integration | Required headers and build dependencies, compiler and platform support, how results are represented, status and error handling, and API stability for the version you will deploy. |
| Operations | Memory needs, allocation behavior, latency distribution, failure statuses, and the effect of constructing the matrix or graph as part of the full production path. |
Release, package, licensing, and platform details vary by library and release and are not established by the cited reference pages. Confirm them against the exact version and target platform you plan to deploy.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Benchmark the workload, not the solver label
The cited documentation offers qualitative guidance, but it does not establish an independently reproducible cross-library production benchmark. A tiny timing comparison in the OR-Tools min-cost-flow example is illustrative documentation, not a controlled basis for ranking solvers. Do not turn it into a general claim about production performance. The example is available here.
Build a benchmark from representative production instances. Give each candidate the same objective and constraints, then compare feasibility and objective values as well as elapsed time. Include the full path from input construction through result extraction so the measurement reflects how the solver will actually be used.
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
- Record instance sizes, graph density, constraint mix, cost ranges, hardware, compiler, and build settings.
- Measure matrix or graph construction, allocation, solving, and result extraction separately where useful, as well as end-to-end latency.
- Capture latency distributions and failure statuses, not only a single run or average.
- Test warm and cold behavior if both occur in deployment.
- Keep enough input and environment detail to reproduce the comparison.
Validate correctness, numeric limits, and failure behavior
Before deployment, confirm what the API’s status actually guarantees and how it represents partial, infeasible, or optimal results. Follow the solver’s documented method for excluding forbidden pairs rather than relying on an undocumented sentinel cost.
Quick Recap
- Check status first. Use assignment results only after the API reports the expected successful status; OR-Tools C++ examples perform an optimal-status check before consuming results.
- Verify the output independently. In a debug or audit path, check every assignment against business constraints and recompute its objective from the original costs.
- Exercise edge cases. Test empty, rectangular, sparse, tied-cost, infeasible, very large, and boundary-numeric inputs as relevant to the model.
- Confirm numeric safety. Check types, scaling, overflow limits, and any solver-specific requirements for costs and capacities against the documentation for the exact implementation.
- Pin deployment details. Record library versions and build options, and verify licensing and platform support for the release actually adopted.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
