20250607 finished.

src/problem/mod.rs

@@ -696,3 +696,5 @@ mod p3403_find_the_lexicographically_largest_string_from_the_box_i;
 mod p1061_lexicographically_smallest_equivalent_string;
 
 mod p2434_using_a_robot_to_print_the_lexicographically_smallest_string;
+
+mod p3170_lexicographically_minimum_string_after_removing_stars;

src/problem/p3170_lexicographically_minimum_string_after_removing_stars.rs

@@ -0,0 +1,73 @@
+/**
+ * [3170] Lexicographically Minimum String After Removing Stars
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::cmp::Ordering;
+use std::collections::BinaryHeap;
+
+#[derive(Eq, PartialEq)]
+struct CharacterPos {
+    char: u8,
+    pos: usize,
+}
+
+impl Ord for CharacterPos {
+    fn cmp(&self, other: &Self) -> Ordering {
+        match other.char.cmp(&self.char) {
+            Ordering::Equal => self.pos.cmp(&other.pos),
+            Ordering::Greater => Ordering::Greater,
+            Ordering::Less => Ordering::Less,
+        }
+    }
+}
+
+impl PartialOrd for CharacterPos {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Solution {
+    pub fn clear_stars(s: String) -> String {
+        // Use the binary head to store the minimal and nearest character.
+        let mut heap = BinaryHeap::new();
+        // The array stores the tuple (character, is_removed).
+        let mut buffer: Vec<(u8, bool)> = s.bytes().map(|x| (x, false)).collect();
+
+        for (i, v) in s.bytes().enumerate() {
+            if v != b'*' {
+                heap.push(CharacterPos { char: v, pos: i });
+            } else {
+                // Remove the star character firstly.
+                buffer.get_mut(i).unwrap().1 = true;
+
+                // Then find the nearest and minimal character.
+                let head = heap.pop().unwrap();
+                buffer.get_mut(head.pos).unwrap().1 = true;
+            }
+        }
+
+        String::from_utf8(
+            buffer
+                .into_iter()
+                .filter_map(|(c, f)| if f { None } else { Some(c) })
+                .collect(),
+        )
+        .unwrap()
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_3170() {
+        assert_eq!("aab", Solution::clear_stars("aaba*".to_string()));
+        assert_eq!("abc", Solution::clear_stars("abc".to_string()));
+    }
+}