Create: 0621-task-scheduler.rs

Author: Jay-0331

rust/0621-task-scheduler.rs

@@ -0,0 +1,34 @@
+use std::collections::{BinaryHeap, VecDeque, HashMap};
+
+impl Solution {
+    pub fn least_interval(tasks: Vec<char>, n: i32) -> i32 {
+        let mut count = HashMap::new();
+        let mut max_heap = BinaryHeap::new();
+        for task in tasks {
+            let count = count.entry(task).or_insert(0);
+            *count += 1;
+        }
+        for (key, val) in count.iter() {
+            max_heap.push(*val);
+        }
+        let mut time = 0;
+        let mut deque: VecDeque<(i32,i32)> = VecDeque::new();
+        while deque.len() > 0 || max_heap.len() > 0 {
+            time += 1;
+
+            if max_heap.len() == 0 {
+                time = deque[0].1;
+            }
+            else {
+                let cnt = max_heap.pop().unwrap() - 1;
+                if cnt != 0 {
+                    deque.push_back((cnt, time + n));
+                }
+            }
+            if deque.len() > 0 && deque[0].1 == time {
+                max_heap.push(deque.pop_front().unwrap().0);
+            }
+        }
+        time
+    }
+}