Add problem 2337: Move Pieces to Obtain a String

src/lib.rs

@@ -1735,6 +1735,7 @@ pub mod problem_2327_number_of_people_aware_of_a_secret;
 pub mod problem_2331_evaluate_boolean_binary_tree;
 pub mod problem_2335_minimum_amount_of_time_to_fill_cups;
 pub mod problem_2336_smallest_number_in_infinite_set;
+pub mod problem_2337_move_pieces_to_obtain_a_string;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_2337_move_pieces_to_obtain_a_string/greedy.rs

@@ -0,0 +1,84 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn can_change(start: String, target: String) -> bool {
+        let top = start.as_bytes();
+        let bottom = target.as_bytes();
+        let mut i = 0;
+        let mut j = 0;
+
+        while let Some(&y) = bottom.get(j) {
+            match y {
+                b'L' => loop {
+                    if let Some(&x) = top.get(i) {
+                        match x {
+                            b'L' => {
+                                if i < j {
+                                    return false;
+                                }
+
+                                i += 1;
+
+                                break;
+                            }
+                            b'R' => return false,
+                            _ => i += 1,
+                        }
+                    } else {
+                        return false;
+                    }
+                },
+                b'R' => {
+                    let window = &top[..=j];
+
+                    loop {
+                        if let Some(&x) = window.get(i) {
+                            match x {
+                                b'L' => return false,
+                                b'R' => {
+                                    i += 1;
+
+                                    break;
+                                }
+                                _ => i += 1,
+                            }
+                        } else {
+                            return false;
+                        }
+                    }
+                }
+                _ => {}
+            }
+
+            j += 1;
+        }
+
+        while let Some(&c) = top.get(i) {
+            if c != b'_' {
+                return false;
+            }
+
+            i += 1;
+        }
+
+        true
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn can_change(start: String, target: String) -> bool {
+        Self::can_change(start, target)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2337_move_pieces_to_obtain_a_string/mod.rs

@@ -0,0 +1,26 @@
+pub mod greedy;
+
+pub trait Solution {
+    fn can_change(start: String, target: String) -> bool;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            (("_L__R__R_", "L______RR"), true),
+            (("R_L_", "__LR"), false),
+            (("_R", "R_"), false),
+            (("_LL__R__R_", "L___L___RR"), false),
+            (("_", "L"), false),
+            (("L___L_", "_RR___"), false),
+            (("_L__R__R_L", "L______RR_"), false),
+        ];
+
+        for ((start, target), expected) in test_cases {
+            assert_eq!(S::can_change(start.to_string(), target.to_string()), expected);
+        }
+    }
+}