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use super::{ Puzzle, MAXN };
impl Puzzle {
pub fn new(N: usize) -> Puzzle {
Puzzle {
in_col: [0; MAXN],
per_row: [0; MAXN],
per_d1: [0; 2 * MAXN - 1],
per_d2: [0; 2 * MAXN - 1],
N: N,
rng: rand::thread_rng(),
}
}
pub fn clear(&mut self) {
for i in 0..2 * self.N - 1 {
if i < self.N {
self.in_col[i] = 0;
self.per_row[i] = 0;
}
else if i < MAXN {
assert_eq!(self.in_col[i], 0, "Someone wrote to in_col at index {}!", i);
assert_eq!(self.per_row[i], 0, "Someone wrote to per_row at index {}!", i);
}
self.per_d1[i] = 0;
self.per_d2[i] = 0;
}
}
/// O(1)
pub fn attacks(&self, col: usize, row: usize) -> i32 {
assert!(col < self.N && row < self.N, "Bad attacks index: {} {}!", col, row);
1 + // Always a queen on a column
self.per_row[row] + // Queens on the row
self.per_d1[col + self.N - 1 - row] +
self.per_d2[col + row]
- 3 * ((self.in_col[col] == row) as i32)
// If we're in the cell with a queen, remove repeated counts of it
}
// | |*| | | |2|3|2|4|
// | | |*| | |3|2|4|2|
// | | | |*| |2|4|2|3|
// |*| | | | |2|2|3|2|
pub fn example1() -> Puzzle {
let mut r = Puzzle::new(4);
r.in_col[0] = 3;
r.in_col[1] = 0;
r.in_col[2] = 1;
r.in_col[3] = 2;
r.per_row[0] = 1; r.per_row[1] = 1; r.per_row[2] = 1; r.per_row[3] = 1;
r.per_d1[0] = 1;
r.per_d1[4] = 3;
r.per_d2[1] = 1;
r.per_d2[3] = 2;
r.per_d2[5] = 1;
r
}
// |*|*| | | |3|3|3|3|
// | | | | | |2|3|3|2|
// | | |*|*| |3|3|3|3|
// | | | | | |1|2|2|3|
pub fn example2() -> Puzzle {
let mut r = Puzzle::new(4);
r.in_col[0] = 0;
r.in_col[1] = 0;
r.in_col[2] = 2;
r.in_col[3] = 2;
r.per_row[0] = 2; r.per_row[1] = 0; r.per_row[2] = 2; r.per_row[3] = 0;
r.per_d1[3] = 2;
r.per_d1[4] = 2;
r.per_d2[0] = 1;
r.per_d2[1] = 1;
r.per_d2[4] = 1;
r.per_d2[5] = 1;
r
}
}
#[test]
fn test_attacks() {
let e1 = Puzzle::example1();
assert_eq!(e1.attacks(0, 0), 2, "Bad attacks!"); // top-left
assert_eq!(e1.attacks(0, 1), 3, "Bad attacks!"); // below top-left
assert_eq!(e1.attacks(0, 2), 2, "Bad attacks!");
assert_eq!(e1.attacks(0, 3), 2, "Bad attacks!");
assert_eq!(e1.attacks(1, 0), 3, "Bad attacks!"); // right of top-left
assert_eq!(e1.attacks(1, 1), 2, "Bad attacks!");
assert_eq!(e1.attacks(1, 2), 4, "Bad attacks!");
assert_eq!(e1.attacks(1, 3), 2, "Bad attacks!");
assert_eq!(e1.attacks(2, 0), 2, "Bad attacks!");
assert_eq!(e1.attacks(2, 1), 4, "Bad attacks!");
assert_eq!(e1.attacks(2, 2), 2, "Bad attacks!");
assert_eq!(e1.attacks(2, 3), 3, "Bad attacks!");
assert_eq!(e1.attacks(3, 0), 4, "Bad attacks!");
assert_eq!(e1.attacks(3, 1), 2, "Bad attacks!");
assert_eq!(e1.attacks(3, 2), 3, "Bad attacks!");
assert_eq!(e1.attacks(3, 3), 2, "Bad attacks!");
let e2 = Puzzle::example2();
assert_eq!(e2.attacks(0, 0), 3, "Bad attacks!"); // top-left
assert_eq!(e2.attacks(0, 1), 2, "Bad attacks!"); // below top-left
assert_eq!(e2.attacks(0, 2), 3, "Bad attacks!");
assert_eq!(e2.attacks(0, 3), 1, "Bad attacks!");
assert_eq!(e2.attacks(1, 0), 3, "Bad attacks!"); // right of top-left
assert_eq!(e2.attacks(1, 1), 3, "Bad attacks!");
assert_eq!(e2.attacks(1, 2), 3, "Bad attacks!");
assert_eq!(e2.attacks(1, 3), 2, "Bad attacks!");
assert_eq!(e2.attacks(2, 0), 3, "Bad attacks!");
assert_eq!(e2.attacks(2, 1), 3, "Bad attacks!");
assert_eq!(e2.attacks(2, 2), 3, "Bad attacks!");
assert_eq!(e2.attacks(2, 3), 2, "Bad attacks!");
assert_eq!(e2.attacks(3, 0), 3, "Bad attacks!");
assert_eq!(e2.attacks(3, 1), 2, "Bad attacks!");
assert_eq!(e2.attacks(3, 2), 3, "Bad attacks!");
assert_eq!(e2.attacks(3, 3), 3, "Bad attacks!");
}
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