Add problem 3120: Count the Number of Special Characters I

Author: EFanZh

src/lib.rs

@@ -2095,6 +2095,7 @@ pub mod problem_3110_score_of_a_string;
 pub mod problem_3111_minimum_rectangles_to_cover_points;
 pub mod problem_3114_latest_time_you_can_obtain_after_replacing_characters;
 pub mod problem_3115_maximum_prime_difference;
+pub mod problem_3120_count_the_number_of_special_characters_i;
 pub mod problem_3350_adjacent_increasing_subarrays_detection_ii;
 
 #[cfg(test)]

src/problem_3120_count_the_number_of_special_characters_i/bit_manipulation.rs

@@ -0,0 +1,33 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn number_of_special_chars(word: String) -> i32 {
+        let mut states = [0_u32; 2];
+
+        for c in word.into_bytes() {
+            states[usize::from(c >> 5) & 1] |= 1 << (c & 31);
+        }
+
+        let [upper_cases, lower_cases] = states;
+
+        (upper_cases & lower_cases).count_ones().cast_signed()
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn number_of_special_chars(word: String) -> i32 {
+        Self::number_of_special_chars(word)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_3120_count_the_number_of_special_characters_i/mod.rs

@@ -0,0 +1,18 @@
+pub mod bit_manipulation;
+
+pub trait Solution {
+    fn number_of_special_chars(word: String) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [("aaAbcBC", 3), ("abc", 0), ("abBCab", 1)];
+
+        for (word, expected) in test_cases {
+            assert_eq!(S::number_of_special_chars(word.to_string()), expected);
+        }
+    }
+}