20250411 finished.

src/problem/mod.rs

@@ -591,3 +591,5 @@ mod p3396_minimum_number_of_operations_to_make_elements_in_array_distinct;
 
 mod p2999_count_the_number_of_powerful_integers;
 mod p3375_minimum_operations_to_make_array_values_equal_to_k;
+
+mod p2843_count_symmetric_integers;

src/problem/p2843_count_symmetric_integers.rs

@@ -0,0 +1,42 @@
+/**
+ * [2843]   Count Symmetric Integers
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn count_symmetric_integers(low: i32, high: i32) -> i32 {
+        // 10 -> 99 1000 -> 9999
+        (low..=high)
+            .filter_map(|i| {
+                if i >= 10 && i <= 99 {
+                    if i / 10 == i % 10 {
+                        return Some(());
+                    }
+                }
+
+                if i >= 1000 && i <= 9999 {
+                    if i / 1000 + (i / 100) % 10 == (i / 10) % 10 + i % 10 {
+                        return Some(());
+                    }
+                }
+
+                None
+            })
+            .count() as i32
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2843() {
+        assert_eq!(9, Solution::count_symmetric_integers(1, 99));
+        assert_eq!(4, Solution::count_symmetric_integers(1200, 1230));
+    }
+}