CSP Solver

A Constraint Satisfaction Problem (CSP) solver library written in Rust.

Overview

This library provides efficient algorithms and data structures for solving constraint satisfaction problems. CSPs are mathematical problems defined as a set of objects whose state must satisfy a number of constraints or limitations.

Type of variables: float, int, mixed (int and float)

Constraints supported include:

• Arithmetic: +, -, *, /
• Comparisons: <, <=, >, >=, ==, !=
• all_different

Installation

Add this to your Cargo.toml:

[dependencies]
cspsolver = "0.3.12"

Examples

cargo run --example sudoku
cargo run --example pc_builder
cargo run --example resource_allocation
cargo run --example portfolio_optimization

🧩 Solving PLATINUM puzzle:
📊 Puzzle stats: 17 clues given, 64 empty cells

Puzzle:
┌───────┬───────┬───────┐
│ · · · │ · · · │ · · · │
│ · · · │ · · 3 │ · 8 5 │
│ · · 1 │ · 2 · │ · · · │
├───────┼───────┼───────┤
│ · · · │ 5 · 7 │ · · · │
│ · · 4 │ · · · │ 1 · · │
│ · 9 · │ · · · │ · · · │
├───────┼───────┼───────┤
│ 5 · · │ · · · │ · 7 3 │
│ · · 2 │ · 1 · │ · · · │
│ · · · │ · 4 · │ · · 9 │
└───────┴───────┴───────┘
✅ Solution found in 144330.511ms!
📊 Statistics: 638 propagations, 54 nodes explored
🔍 Efficiency: 11.8 propagations/node

Solution:
┌───────┬───────┬───────┐
│ 9 8 7 │ 6 5 4 │ 3 2 1 │
│ 2 4 6 │ 1 7 3 │ 9 8 5 │
│ 3 5 1 │ 9 2 8 │ 7 4 6 │
├───────┼───────┼───────┤
│ 1 2 8 │ 5 3 7 │ 6 9 4 │
│ 6 3 4 │ 8 9 2 │ 1 5 7 │
│ 7 9 5 │ 4 6 1 │ 8 3 2 │
├───────┼───────┼───────┤
│ 5 1 9 │ 2 8 6 │ 4 7 3 │
│ 4 7 2 │ 3 1 9 │ 5 6 8 │
│ 8 6 3 │ 7 4 5 │ 2 1 9 │
└───────┴───────┴───────┘

Basic Usage

use cspsolver::prelude::*;

fn main() {
    // constraint: v0(int) * 1.5 < 5.0
    // solving for maximum v0
    let mut m = Model::default();

    let v0 = m.new_var_int(1, 3);
    println!("v0 domain: [1, 3]");

    m.less_than(v0.times_pos(float(1.5)), float(5.0));

    let solution = m.maximize(v0).unwrap();
    let x = match solution[v0] {
        Val::ValI(int_val) => int_val,
        _ => panic!("Expected integer value"),
    };

    assert!(x == 3);
    println!("Found optimal value: {}", x);
}

Status

The new implementation follows the design and implementation of Copper v0.1.0.

The library is currently in active development. Features and APIs may change as we refine the implementation and add new functionality.

License

This project is licensed under the MIT License - see the LICENSE file for details.