Add problem 2375: Construct Smallest Number From DI String

Author: EFanZh

src/lib.rs

@@ -1768,6 +1768,7 @@ pub mod problem_2369_check_if_there_is_a_valid_partition_for_the_array;
 pub mod problem_2370_longest_ideal_subsequence;
 pub mod problem_2373_largest_local_values_in_a_matrix;
 pub mod problem_2374_node_with_highest_edge_score;
+pub mod problem_2375_construct_smallest_number_from_di_string;
 pub mod problem_2379_minimum_recolors_to_get_k_consecutive_black_blocks;
 pub mod problem_2380_time_needed_to_rearrange_a_binary_string;
 pub mod problem_2381_shifting_letters_ii;

src/problem_2375_construct_smallest_number_from_di_string/greedy.rs

@@ -0,0 +1,59 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn smallest_number(pattern: String) -> String {
+        let n = pattern.len();
+        let mut result = String::with_capacity(n + 1);
+        let mut prev = b'I';
+        let mut length = 0;
+        let mut c = b'1';
+
+        for direction in pattern.bytes() {
+            if direction == prev {
+                length += 1;
+            } else {
+                if prev == b'I' {
+                    result.extend((c - length..c).map(char::from));
+                    length = 1;
+                } else {
+                    result.extend((c - length..=c).map(char::from).rev());
+                    length = 0;
+                }
+
+                prev = direction;
+            }
+
+            c += 1;
+        }
+
+        drop(pattern);
+
+        let iter = (c - length..=c).map(char::from);
+
+        if prev == b'I' {
+            result.extend(iter);
+        } else {
+            result.extend(iter.rev());
+        }
+
+        result
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn smallest_number(pattern: String) -> String {
+        Self::smallest_number(pattern)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2375_construct_smallest_number_from_di_string/greedy_2.rs

@@ -0,0 +1,69 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn smallest_number(pattern: String) -> String {
+        let n = pattern.len();
+        let mut result = String::with_capacity(n + 1);
+        let mut length = 0;
+        let mut c = b'1';
+        let mut iter = pattern.bytes();
+
+        'outer: loop {
+            if let Some(direction) = iter.next() {
+                if direction == b'I' {
+                    length += 1;
+                    c += 1;
+                } else {
+                    result.extend((c - length..c).map(char::from));
+
+                    length = 2;
+                    c += 2;
+
+                    loop {
+                        if let Some(direction) = iter.next() {
+                            if direction == b'I' {
+                                break;
+                            }
+
+                            length += 1;
+                            c += 1;
+                        } else {
+                            result.extend((c - length..c).map(char::from).rev());
+
+                            break 'outer;
+                        }
+                    }
+
+                    result.extend((c - length..c).map(char::from).rev());
+                    length = 0;
+                }
+            } else {
+                result.extend((c - length..=c).map(char::from));
+
+                break;
+            }
+        }
+
+        drop(pattern);
+
+        result
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn smallest_number(pattern: String) -> String {
+        Self::smallest_number(pattern)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2375_construct_smallest_number_from_di_string/mod.rs

@@ -0,0 +1,19 @@
+pub mod greedy;
+pub mod greedy_2;
+
+pub trait Solution {
+    fn smallest_number(pattern: String) -> String;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [("IIIDIDDD", "123549876"), ("DDD", "4321"), ("DDDIII", "4321567")];
+
+        for (pattern, expected) in test_cases {
+            assert_eq!(S::smallest_number(pattern.to_string()), expected);
+        }
+    }
+}