csp-solver 0.1.0

Generic constraint satisfaction problem solver with backtracking, AC-3 constraint propagation, and ordering heuristics.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36

//! Simple LCG PRNG (no external dependencies).

pub(crate) struct SimpleRng(u64);

impl SimpleRng {
    pub fn new(seed: u64) -> Self {
        Self(seed)
    }

    pub fn from_time() -> Self {
        let seed = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .unwrap()
            .as_nanos() as u64;
        Self::new(seed)
    }

    pub fn next_u64(&mut self) -> u64 {
        self.0 = self
            .0
            .wrapping_mul(6364136223846793005)
            .wrapping_add(1442695040888963407);
        self.0
    }

    pub fn next_usize(&mut self, bound: usize) -> usize {
        (self.next_u64() % bound as u64) as usize
    }

    pub fn shuffle<T>(&mut self, slice: &mut [T]) {
        for i in (1..slice.len()).rev() {
            let j = self.next_usize(i + 1);
            slice.swap(i, j);
        }
    }
}