Added Employee Free Time

Author: ryanoneill

src/employee_free_time.rs

@@ -0,0 +1,121 @@
+use crate::interval::Interval;
+use std::cmp::Reverse;
+use std::collections::BinaryHeap;
+
+/// We are given a list `schedule` of employees, which represents the working time for each
+/// employee.
+///
+/// Each employee has a list of non-overlapping `Intervals`, and these intervals are in sorted
+/// order.
+///
+/// Return the list of finite intervals representing common, positive-length free time for all
+/// employees, also in sorted order.
+struct Solution;
+
+impl Solution {
+
+    pub fn employee_free_time(schedule: Vec<Vec<Interval>>) -> Vec<Interval> {
+        let mut min_heap: BinaryHeap<Reverse<(i32, i32)>> = BinaryHeap::new();
+
+        for employee in schedule {
+            for block in employee {
+               let item = (block.start, block.end);
+               min_heap.push(Reverse(item));
+            }
+        }
+
+        let mut results = vec![];
+        let mut start = -1;
+
+        while !min_heap.is_empty() {
+            let item = min_heap.pop().unwrap().0;
+            let item_start = item.0;
+            let item_end = item.1;
+
+            if start == -1 {
+                // intialization
+                start = item_end;
+            } else if start >= item_start {
+                // covered, extend next good interval if necessary
+                start = start.max(item_end);
+            } else {
+                // open space
+                let end = item_start;
+                let diff = end - start;
+                if diff > 0 {
+                    let interval = Interval::new(start, end);
+                    results.push(interval);
+                }
+                start = item_end;
+            }
+        }
+
+        results
+    }
+
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::interval::Interval;
+    use super::Solution;
+
+    #[test]
+    fn example_1() {
+        let schedule = vec![
+            vec![
+                Interval::new(1, 2),
+                Interval::new(5, 6),
+            ],
+            vec![
+                Interval::new(1, 3),
+                Interval::new(4, 10),
+            ]
+        ];
+        let results = Solution::employee_free_time(schedule);
+        assert_eq!(results.len(), 1);
+        assert_eq!(results, vec![Interval::new(3,4)]);
+    }
+
+    #[test]
+    fn example_2() {
+        let schedule = vec![
+            vec![
+                Interval::new(1,3),
+                Interval::new(6,7),
+            ],
+            vec![
+                Interval::new(2,4),
+            ],
+            vec![
+                Interval::new(2,5),
+                Interval::new(9,12),
+            ]
+        ];
+        let results = Solution::employee_free_time(schedule);
+        assert_eq!(results.len(), 2);
+        assert_eq!(results, vec![Interval::new(5,6), Interval::new(7,9)]);
+    }
+
+    #[test]
+    fn example_3() {
+        let schedule = vec![
+            vec![
+                Interval::new(45,56),
+                Interval::new(89,96),
+            ],
+            vec![
+                Interval::new(5,21),
+                Interval::new(57,74),
+            ],
+        ];
+        let results = Solution::employee_free_time(schedule);
+        assert_eq!(results.len(), 3);
+        assert_eq!(results, vec![
+            Interval::new(21,45),
+            Interval::new(56,57),
+            Interval::new(74,89),
+        ]);
+    }
+
+}

src/interval.rs

@@ -0,0 +1,15 @@
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub struct Interval {
+    pub start: i32,
+    pub end: i32
+}
+
+impl Interval {
+    #[inline]
+    pub fn new(start: i32, end: i32) -> Self {
+        Self {
+            start,
+            end
+        }
+    }
+}

src/lib.rs

@@ -27,6 +27,7 @@ macro_rules! assert_tree {
     };
 }
 
+pub mod interval;
 pub mod kth_largest;
 pub mod lowercase_letter_counter;
 pub mod list_node;
@@ -542,7 +543,7 @@ pub mod min_cost_climbing_stairs; // 746
 pub mod open_the_lock; // 752 ✓
 
 pub mod bold_words_in_string; // 758 ✓
-
+pub mod employee_free_time; // 759 ✓
 pub mod find_anagram_mappings; // 760 ✓
 
 pub mod jewels_and_stones; // 771