Struct Knapsack 

pub struct Knapsack { /* private fields */ }

The 0-1 Knapsack problem.

Given n items, each with nonnegative weight w_i and nonnegative value v_i, and a nonnegative capacity C, find a subset S ⊆ {0, ..., n-1} such that ∑_{i∈S} w_i ≤ C, maximizing ∑_{i∈S} v_i.

Representation

Each item has a binary variable: x_i = 1 if item i is selected, 0 otherwise.

Example

use problemreductions::models::misc::Knapsack;
use problemreductions::{Problem, Solver, BruteForce};

let problem = Knapsack::new(vec![2, 3, 4, 5], vec![3, 4, 5, 7], 7);
let solver = BruteForce::new();
let solution = solver.find_best(&problem);
assert!(solution.is_some());

Implementations

impl Knapsack

pub fn new(weights: Vec<i64>, values: Vec<i64>, capacity: i64) -> Self

Create a new Knapsack instance.

Panics

Panics if weights and values have different lengths, or if any weight, value, or the capacity is negative.

pub fn weights(&self) -> &[i64]

Returns the item weights.

pub fn values(&self) -> &[i64]

Returns the item values.

pub fn capacity(&self) -> i64

Returns the knapsack capacity.

pub fn num_items(&self) -> usize

Returns the number of items.

pub fn num_slack_bits(&self) -> usize

Returns the number of binary slack bits used by the QUBO encoding.

For positive capacity this is floor(log2(C)) + 1; for zero capacity we keep one slack bit so the encoding shape remains uniform.

Trait Implementations

impl Clone for Knapsack

fn clone(&self) -> Knapsack

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Knapsack

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Knapsack

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl OptimizationProblem for Knapsack

type Value = i64

The inner objective value type (e.g., i32, f64).

fn direction(&self) -> Direction

Whether to maximize or minimize the metric.

impl Problem for Knapsack

const NAME: &'static str = "Knapsack"

Base name of this problem type (e.g., “MaximumIndependentSet”).

type Metric = SolutionSize<i64>

The evaluation metric type.

fn variant() -> Vec<(&'static str, &'static str)>

Returns variant attributes derived from type parameters.

fn dims(&self) -> Vec<usize>

Configuration space dimensions. Each entry is the cardinality of that variable.

fn evaluate(&self, config: &[usize]) -> SolutionSize<i64>

Evaluate the problem on a configuration.

fn num_variables(&self) -> usize

Number of variables (derived from dims).

fn problem_type() -> ProblemType

Look up this problem’s catalog entry.

impl ReduceTo<QUBO> for Knapsack

type Result = ReductionKnapsackToQUBO

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl Serialize for Knapsack

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl DeclaredVariant for Knapsack