assignment/
assignment.rs

1extern crate lp_modeler;
2
3use std::collections::HashMap;
4
5use lp_modeler::dsl::*;
6use lp_modeler::solvers::{SolverTrait, CbcSolver};
7
8fn main() {
9    // Problem Data
10    let men = vec!["A", "B", "C"];
11    let women = vec!["D", "E", "F"];
12    let compatibility_score: HashMap<(&str, &str),f32> = vec![
13        (("A", "D"), 50.0),
14        (("A", "E"), 75.0),
15        (("A", "F"), 75.0),
16        (("B", "D"), 60.0),
17        (("B", "E"), 95.0),
18        (("B", "F"), 80.0),
19        (("C", "D"), 60.0),
20        (("C", "E"), 70.0),
21        (("C", "F"), 80.0),
22    ].into_iter().collect();
23
24    // Define Problem
25    let mut problem = LpProblem::new("Matchmaking", LpObjective::Maximize);
26
27    // Define Variables
28    let vars: HashMap<(&str,&str), LpBinary> =
29        men.iter()
30            .flat_map(|&m| women.iter()
31            .map(move |&w| {
32                let key = (m,w);
33                let value = LpBinary::new(&format!("{}_{}", m,w));
34                (key, value)
35            }))
36            .collect();
37
38    // Define Objective Function
39    let obj_vec: Vec<LpExpression> = {
40       vars.iter().map( |(&(m,w), bin)| {
41           let &coef = compatibility_score.get(&(m, w)).unwrap();
42           coef * bin
43       } )
44    }.collect();
45    problem += obj_vec.sum();
46
47    // Define Constraints
48    // - constraint 1: Each man must be assigned to exactly one woman
49    for &m in &men{
50        problem += sum(&women, |&w| vars.get(&(m,w)).unwrap() ).equal(1);
51    }
52
53    // - constraint 2: Each woman must be assigned to exactly one man
54    for &w in &women{
55        problem += sum(&men, |&m| vars.get(&(m,w)).unwrap() ).equal(1);
56    }
57
58    // Run Solver
59    let solver = CbcSolver::new();
60    let result = solver.run(&problem);
61
62    // Compute final objective function value
63    // (terminate if error, or assign status & variable values)
64    assert!(result.is_ok(), result.unwrap_err());
65    let solution = result.unwrap();
66    let mut obj_value = 0f32;
67    for (&(m, w), var) in &vars{
68        let obj_coef = compatibility_score.get(&(m, w)).unwrap();
69        let var_value = solution.results.get(&var.name).unwrap();
70
71        obj_value += obj_coef * var_value;
72    }
73
74    // Print output
75    println!("Status: {:?}", solution.status);
76    println!("Objective Value: {}", obj_value);
77    for (var_name, var_value) in &solution.results{
78        let int_var_value = *var_value as u32;
79        if int_var_value == 1{
80            println!("{} = {}", var_name, int_var_value);
81        }
82    }
83}
84
assignment/assignment.rs

assignment/
assignment.rs
