20250417 finished.

src/problem/mod.rs

@@ -603,3 +603,5 @@ mod p1534_count_good_triplets;
 mod p2179_count_good_triplets_in_an_array;
 
 mod p2537_count_the_number_of_good_subarrays;
+
+mod p2176_count_equal_and_divisible_pairs_in_an_array;

src/problem/p2176_count_equal_and_divisible_pairs_in_an_array.rs

@@ -0,0 +1,39 @@
+/**
+ * [2176] Count Equal and Divisible Pairs in an Array
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn count_pairs(nums: Vec<i32>, k: i32) -> i32 {
+        let k = k as usize;
+        let n = nums.len();
+
+        (0..n)
+            .into_iter()
+            .map(|x| (x + 1..n).into_iter().map(move |y| (x, y)))
+            .flatten()
+            .filter_map(|(i, j)| {
+                if nums[i] == nums[j] && i * j % k == 0 {
+                    Some(())
+                } else {
+                    None
+                }
+            })
+            .count() as i32
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2176() {
+        assert_eq!(4, Solution::count_pairs(vec![3, 1, 2, 2, 2, 1, 3], 2));
+        assert_eq!(0, Solution::count_pairs(vec![1, 2, 3, 4], 1));
+    }
+}