[#wallet-KnapsackSolver]
= xref:wallet.adoc[wallet]::KnapsackSolver
:relfileprefix: ../
:mrdocs:

Select coins using the original Knapsack approximation, used as a fallback.

== Synopsis

Declared in `<wallet/coinselection.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:util/Result.adoc[util::Result<SelectionResult>]
KnapsackSolver(
    std::vector<OutputGroup>& groups,
    xref:CAmount.adoc[CAmount] const& nTargetValue,
    xref:CAmount.adoc[CAmount] change_target,
    xref:FastRandomContext.adoc[FastRandomContext]& rng,
    int max_selection_weight);
----

== Return Value

If successful, a valid SelectionResult, otherwise util::Error.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *groups*
| The output groups eligible for selection.
| *nTargetValue*
| The target value to select for.
| *change_target*
| The minimum change amount to target.
| *rng*
| The randomness source used during selection.
| *max_selection_weight*
| The maximum allowed weight for a valid selection.
|===


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