Add problem 2352: Equal Row and Column Pairs

src/lib.rs

@@ -1743,6 +1743,7 @@ pub mod problem_2347_best_poker_hand;
 pub mod problem_2348_number_of_zero_filled_subarrays;
 pub mod problem_2349_design_a_number_container_system;
 pub mod problem_2351_first_letter_to_appear_twice;
+pub mod problem_2352_equal_row_and_column_pairs;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_2352_equal_row_and_column_pairs/hash_map.rs

@@ -0,0 +1,53 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+use std::collections::hash_map::Entry;
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn equal_pairs(grid: Vec<Vec<i32>>) -> i32 {
+        let mut counts = HashMap::new();
+
+        for row in &grid {
+            match counts.entry(&**row) {
+                Entry::Occupied(occupied_entry) => *occupied_entry.into_mut() += 1,
+                Entry::Vacant(vacant_entry) => {
+                    vacant_entry.insert(1);
+                }
+            }
+        }
+
+        let mut result = 0;
+        let n = grid.len();
+        let mut buffer = Vec::with_capacity(n);
+
+        for x in 0..n {
+            buffer.extend(grid.iter().map(|row| row[x]));
+
+            if let Some(count) = counts.get(&*buffer) {
+                result += count;
+            }
+
+            buffer.clear();
+        }
+
+        result
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn equal_pairs(grid: Vec<Vec<i32>>) -> i32 {
+        Self::equal_pairs(grid)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2352_equal_row_and_column_pairs/mod.rs

@@ -0,0 +1,22 @@
+pub mod hash_map;
+
+pub trait Solution {
+    fn equal_pairs(grid: Vec<Vec<i32>>) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+    use crate::test_utilities::Matrix;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            (&[[3, 2, 1], [1, 7, 6], [2, 7, 7]] as &dyn Matrix<_>, 1),
+            (&[[3, 1, 2, 2], [1, 4, 4, 5], [2, 4, 2, 2], [2, 4, 2, 2]], 3),
+        ];
+
+        for (grid, expected) in test_cases {
+            assert_eq!(S::equal_pairs(grid.to_vec()), expected);
+        }
+    }
+}