Add problem 3169: Count Days Without Meetings

Author: EFanZh

src/lib.rs

@@ -2118,6 +2118,7 @@ pub mod problem_3162_find_the_number_of_good_pairs_i;
 pub mod problem_3163_string_compression_iii;
 pub mod problem_3164_find_the_number_of_good_pairs_ii;
 pub mod problem_3168_minimum_number_of_chairs_in_a_waiting_room;
+pub mod problem_3169_count_days_without_meetings;
 pub mod problem_3350_adjacent_increasing_subarrays_detection_ii;
 
 #[cfg(test)]

src/problem_3169_count_days_without_meetings/mod.rs

@@ -0,0 +1,23 @@
+pub mod sweep_line;
+
+pub trait Solution {
+    fn count_days(days: i32, meetings: Vec<Vec<i32>>) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            ((10, &[[5, 7], [1, 3], [9, 10]] as &[_]), 2),
+            ((5, &[[2, 4], [1, 3]]), 1),
+            ((6, &[[1, 6]]), 0),
+            ((8, &[[3, 4], [4, 8], [2, 5], [3, 8]]), 1),
+        ];
+
+        for ((days, meetings), expected) in test_cases {
+            assert_eq!(S::count_days(days, meetings.iter().map(Vec::from).collect()), expected,);
+        }
+    }
+}

src/problem_3169_count_days_without_meetings/sweep_line.rs

@@ -0,0 +1,55 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn count_days(days: i32, meetings: Vec<Vec<i32>>) -> i32 {
+        let days = days.cast_unsigned();
+
+        let mut meetings = meetings
+            .into_iter()
+            .flat_map(|meeting| {
+                let [start, end] = <[_; 2]>::map(meeting.try_into().ok().unwrap(), i32::cast_unsigned);
+
+                [start << 2, (end << 2) | 2]
+            })
+            .collect::<Box<_>>();
+
+        meetings.sort_unstable();
+
+        let mut result = 0;
+        let mut start = 1;
+        let mut count = 0;
+
+        for event in meetings {
+            count = count + 1 - (event & 3);
+
+            if count == 0 {
+                start = (event >> 2) + 1;
+            } else if start != 0 {
+                result += (event >> 2) - start;
+                start = 0;
+            }
+        }
+
+        result += days + 1 - start;
+
+        result.cast_signed()
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn count_days(days: i32, meetings: Vec<Vec<i32>>) -> i32 {
+        Self::count_days(days, meetings)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}