Add problem 1876: Substrings of Size Three with Distinct Characters

src/lib.rs

@@ -1441,6 +1441,7 @@ pub mod problem_1860_incremental_memory_leak;
 pub mod problem_1861_rotating_the_box;
 pub mod problem_1864_minimum_number_of_swaps_to_make_the_binary_string_alternating;
 pub mod problem_1869_longer_contiguous_segments_of_ones_than_zeros;
+pub mod problem_1876_substrings_of_size_three_with_distinct_characters;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_1876_substrings_of_size_three_with_distinct_characters/iterative.rs

@@ -0,0 +1,36 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn count_good_substrings(s: String) -> i32 {
+        let mut result = 0;
+        let mut iter = s.bytes();
+        let mut first = iter.next().unwrap();
+        let mut second = first;
+
+        for c in iter {
+            result += i32::from(first != second && first != c && second != c);
+            first = second;
+            second = c;
+        }
+
+        result
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn count_good_substrings(s: String) -> i32 {
+        Self::count_good_substrings(s)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_1876_substrings_of_size_three_with_distinct_characters/mod.rs

@@ -0,0 +1,18 @@
+pub mod iterative;
+
+pub trait Solution {
+    fn count_good_substrings(s: String) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [("xyzzaz", 1), ("aababcabc", 4)];
+
+        for (s, expected) in test_cases {
+            assert_eq!(S::count_good_substrings(s.to_string()), expected);
+        }
+    }
+}