20250222 finished.

src/problem/mod.rs

@@ -498,3 +498,5 @@ mod p624_maximum_distance_in_arrays;
 mod p2595_number_of_even_and_odd_bits;
 
 mod p2209_minimum_white_tiles_after_covering_with_carpets;
+
+mod p2506_count_pairs_of_similar_strings;

src/problem/p2506_count_pairs_of_similar_strings.rs

@@ -0,0 +1,50 @@
+/**
+ * [2506] Count Pairs Of Similar Strings
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn similar_pairs(words: Vec<String>) -> i32 {
+        let mut map = HashMap::new();
+
+        for word in words.iter() {
+            let mut bits = 0;
+
+            for c in word.chars() {
+                bits = bits | (1 << (c as u8 - 'a' as u8))
+            }
+
+            let entry = map.entry(bits).or_insert(0);
+            *entry += 1;
+        }
+
+        let mut result = 0;
+
+        for &v in map.values() {
+            // C(n, 2)
+            result += v * (v - 1) / 2;
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2506() {
+        assert_eq!(
+            2,
+            Solution::similar_pairs(vec_string!("aba", "aabb", "abcd", "bac", "aabc"))
+        );
+        assert_eq!(3, Solution::similar_pairs(vec_string!("aabb", "ab", "ba")));
+        assert_eq!(0, Solution::similar_pairs(vec_string!("nba", "cba", "dba")));
+    }
+}