Add problem 3035: Maximum Palindromes After Operations

Author: EFanZh

src/lib.rs

@@ -2055,6 +2055,7 @@ pub mod problem_3024_type_of_triangle;
 pub mod problem_3026_maximum_good_subarray_sum;
 pub mod problem_3028_ant_on_the_boundary;
 pub mod problem_3033_modify_the_matrix;
+pub mod problem_3035_maximum_palindromes_after_operations;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_3035_maximum_palindromes_after_operations/greedy.rs

@@ -0,0 +1,59 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn max_palindromes_after_operations(words: Vec<String>) -> i32 {
+        let mut counts = [0_u32; 26];
+
+        let mut word_lengths = words
+            .into_iter()
+            .map(|word| {
+                for c in word.bytes() {
+                    counts[usize::from(c) - usize::from(b'a')] += 1;
+                }
+
+                word.len() as u16
+            })
+            .collect::<Vec<_>>();
+
+        let mut even_pairs = 0;
+
+        for count in counts {
+            even_pairs += (count / 2) as u16;
+        }
+
+        word_lengths.sort_unstable();
+
+        word_lengths
+            .iter()
+            .take_while(|&&length| {
+                let required_even_pairs = length / 2;
+
+                if even_pairs < required_even_pairs {
+                    false
+                } else {
+                    even_pairs -= required_even_pairs;
+
+                    true
+                }
+            })
+            .count() as _
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn max_palindromes_after_operations(words: Vec<String>) -> i32 {
+        Self::max_palindromes_after_operations(words)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_3035_maximum_palindromes_after_operations/mod.rs

@@ -0,0 +1,25 @@
+pub mod greedy;
+
+pub trait Solution {
+    fn max_palindromes_after_operations(words: Vec<String>) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            (&["abbb", "ba", "aa"] as &[_], 3),
+            (&["abc", "ab"], 2),
+            (&["cd", "ef", "a"], 1),
+        ];
+
+        for (words, expected) in test_cases {
+            assert_eq!(
+                S::max_palindromes_after_operations(words.iter().copied().map(str::to_string).collect()),
+                expected,
+            );
+        }
+    }
+}