fix diagonals FULLY

src/misc.rs

@@ -15,14 +15,53 @@ where
     if x > min + T::one() {
         let x_lower = x - T::one();
         output.push((min..=x_lower).rev().collect());
+    } else {
+        output.push(Vec::new());
     }
 
     if x + T::one() < max {
         output.push(((x + T::one())..=max).collect());
+    } else {
+        output.push(Vec::new());
     }
     output
 }
 
+pub fn diag(
+    i: usize,
+    j: usize,
+    min_i: usize,
+    min_j: usize,
+    max_i: usize,
+    max_j: usize,
+) -> Vec<Vec<(usize, usize)>> {
+    let i_chains = split_from(min_i, max_i, i);
+    let j_chains = split_from(min_j, max_j, j);
+
+    vec![
+        i_chains[0]
+            .clone()
+            .into_iter()
+            .zip(j_chains[0].clone())
+            .collect(),
+        i_chains[1]
+            .clone()
+            .into_iter()
+            .zip(j_chains[1].clone())
+            .collect(),
+        i_chains[1]
+            .clone()
+            .into_iter()
+            .zip(j_chains[0].clone())
+            .collect(),
+        i_chains[0]
+            .clone()
+            .into_iter()
+            .zip(j_chains[1].clone())
+            .collect(),
+    ]
+}
+
 #[cfg(test)]
 mod test {
     use super::*;
@@ -31,9 +70,9 @@ mod test {
     fn split_test() {
         assert_eq!(split_from(0, 6, 2), vec![vec![1, 0], vec![3, 4, 5, 6]]);
 
-        assert_eq!(split_from(0, 6, 0), vec![vec![1, 2, 3, 4, 5, 6]]);
+        assert_eq!(split_from(0, 6, 0), vec![vec![], vec![1, 2, 3, 4, 5, 6]]);
 
-        assert_eq!(split_from(0, 6, 6), vec![vec![5, 4, 3, 2, 1, 0]]);
+        assert_eq!(split_from(0, 6, 6), vec![vec![5, 4, 3, 2, 1, 0], vec![]]);
 
         // test out-of-bounds and also generics
         assert_eq!(
@@ -41,4 +80,17 @@ mod test {
             Vec::<Vec<i16>>::new()
         );
     }
+
+    #[test]
+    fn diag_test() {
+        assert_eq!(
+            diag(2, 3, 0, 0, 7, 7),
+            vec![
+                vec![(1, 2), (0, 1)],
+                vec![(3, 4), (4, 5), (5, 6), (6, 7)],
+                vec![(3, 2), (4, 1), (5, 0)],
+                vec![(1, 4), (0, 5)]
+            ]
+        );
+    }
 }