iut/scrabble-with-numbers
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Make the is_contiguous check more robust and readable

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This commit is contained in:
Clément Fréville
2023-02-10 20:35:53 +01:00
parent e67a28d110
commit 2920e6614f
1 changed files with 29 additions and 19 deletions
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48
board-shared/src/board.rs
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@@ -29,31 +29,29 @@ impl Board {
diff
}
/// Determines whether the given positions are contiguous.
///
/// Contiguous means that the positions are adjacent in a straight line, either
/// horizontally or vertically.
pub fn is_contiguous(positions: &[Position2d]) -> Option<bool> {
let mut it = positions.iter();
let first = *it.next()?;
let mut second = *it.next()?;
if first.x == second.x {
// Vertical
for &pos in it {
if pos.x != first.x || pos.y != second.y + 1 {
return Some(false);
}
second = pos;
let orientation = match (second.x.checked_sub(first.x), second.y.checked_sub(first.y)) {
(Some(0), Some(1)) => (0, 1),
(Some(1), Some(0)) => (1, 0),
(_, _) => return Some(false),
};
for &pos in it {
if pos.x != second.x + orientation.0 || pos.y != second.y + orientation.1 {
return Some(false);
}
Some(true)
} else if first.y == second.y {
// Horizontal
for &pos in it {
if pos.y != first.y || pos.y != second.y + 1 {
return Some(false);
}
second = pos;
}
Some(true)
} else {
Some(false)
second = pos;
}
Some(true)
}
}
@@ -80,10 +78,22 @@ mod tests {
fn test_is_contiguous() {
assert_eq!(Board::is_contiguous(&[]), None);
assert_eq!(Board::is_contiguous(&positions(&[(0, 0)])), None);
assert_eq!(
Board::is_contiguous(&positions(&[(0, 0), (0, 2)])),
Some(false)
);
assert_eq!(
Board::is_contiguous(&positions(&[(0, 0), (2, 0)])),
Some(false)
);
assert_eq!(
Board::is_contiguous(&positions(&[(0, 0), (0, 1), (0, 2)])),
Some(true)
);
assert_eq!(
Board::is_contiguous(&positions(&[(1, 0), (2, 0), (3, 0), (4, 0)])),
Some(true)
);
assert_eq!(
Board::is_contiguous(&positions(&[(0, 0), (0, 1), (1, 3)])),
Some(false)