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use crate::problem::{CheckInc, Scope};
#[derive(Debug)]
pub struct TotalSum {
n: usize,
domain: Vec<usize>,
sum_at_least: usize,
}
impl TotalSum {
pub fn new(n: usize, domain: &[usize], sum_at_least: usize) -> Self {
TotalSum { n, domain: domain.to_vec(), sum_at_least }
}
}
impl Scope<'_> for TotalSum {
fn size(&self) -> usize {
self.n
}
fn value(&self, index: usize) -> usize {
self.domain[index]
}
fn len(&self) -> usize {
self.domain.len()
}
}
#[derive(Debug, Clone)]
pub struct SumReached {
sum: usize,
last_satisfied: bool,
satisfied: bool,
}
impl CheckInc for TotalSum {
type Accumulator = SumReached;
fn fold_acc(
&self,
accu: Option<Self::Accumulator>,
x: &usize,
_position: usize,
) -> Self::Accumulator {
let mut accu = accu.unwrap_or(SumReached {
sum: 0,
last_satisfied: self.sum_at_least == 0,
satisfied: false,
});
accu.sum += *x;
accu.last_satisfied = accu.satisfied;
accu.satisfied = accu.sum >= self.sum_at_least;
accu
}
fn accu_sat(&self, accu: &Self::Accumulator, x: &usize, position: usize) -> bool {
let last_satisfied = accu.last_satisfied;
if position < self.size() - 1 {
!(*x > 0 && accu.satisfied && last_satisfied)
} else if *x > 0 {
(!last_satisfied) && accu.satisfied
} else {
accu.satisfied
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::problems::utils::sat_safe;
#[test]
fn sums_sat3() {
let sums = TotalSum::new(3, &[4, 2, 0, 1], 4);
assert!(sat_safe(&sums, vec![4]));
assert!(sat_safe(&sums, vec![0, 0, 4]));
assert!(sat_safe(&sums, vec![1, 1, 4]));
assert!(sat_safe(&sums, vec![2, 1, 1]));
assert!(sat_safe(&sums, vec![4, 0, 0]));
}
#[test]
fn sums_sat4() {
let sums = TotalSum::new(4, &[4, 2, 0, 1], 3);
assert!(sat_safe(&sums, vec![4]));
assert!(sat_safe(&sums, vec![0, 2, 2, 0]));
assert!(sat_safe(&sums, vec![1, 1, 0, 1]));
assert!(sat_safe(&sums, vec![2, 0, 2, 0]));
}
#[test]
fn sums_unsat_too_few() {
let sums = TotalSum::new(3, &[4, 0, 1], 4);
assert!(!sat_safe(&sums, vec![0, 0, 0]));
assert!(!sat_safe(&sums, vec![0, 1, 1]));
assert!(!sat_safe(&sums, vec![1, 1, 1]));
}
#[test]
fn sums_unsat_too_many() {
let sums = TotalSum::new(3, &[4, 0, 1], 4);
assert!(!sat_safe(&sums, vec![4, 1, 1]));
assert!(!sat_safe(&sums, vec![4, 0, 1]));
assert!(!sat_safe(&sums, vec![1, 4, 1]));
}
}