Data update

Task/Priority-queue/JavaScript/priority-queue.js

@@ -0,0 +1,96 @@
+class Task {
+    constructor(priority, name) {
+        this.priority = priority;
+        this.name = name;
+    }
+
+    toString() {
+        return `${this.priority}, ${this.name}`;
+    }
+}
+
+class PriorityQueue {
+    constructor() {
+        this.heap = [];
+    }
+
+    // Add a task to the heap
+    add(task) {
+        this.heap.push(task);
+        this.bubbleUp(this.heap.length - 1);
+    }
+
+    // Remove and return the highest priority task
+    remove() {
+        if (this.heap.length === 0) return null;
+        const min = this.heap[0];
+        const end = this.heap.pop();
+        if (this.heap.length > 0) {
+            this.heap[0] = end;
+            this.bubbleDown(0);
+        }
+        return min;
+    }
+
+    // Check if the queue is empty
+    isEmpty() {
+        return this.heap.length === 0;
+    }
+
+    // Move the element at index `i` up the heap
+    bubbleUp(i) {
+        const element = this.heap[i];
+        while (i > 0) {
+            const parentIndex = Math.floor((i - 1) / 2);
+            const parent = this.heap[parentIndex];
+            if (element.priority >= parent.priority) break;
+            this.heap[i] = parent;
+            i = parentIndex;
+        }
+        this.heap[i] = element;
+    }
+
+    // Move the element at index `i` down the heap
+    bubbleDown(i) {
+        const element = this.heap[i];
+        const length = this.heap.length;
+        while (true) {
+            const leftChildIndex = 2 * i + 1;
+            const rightChildIndex = 2 * i + 2;
+            let leftChild, rightChild;
+            let swap = null;
+
+            if (leftChildIndex < length) {
+                leftChild = this.heap[leftChildIndex];
+                if (leftChild.priority < element.priority) {
+                    swap = leftChildIndex;
+                }
+            }
+            if (rightChildIndex < length) {
+                rightChild = this.heap[rightChildIndex];
+                if (
+                    (swap === null && rightChild.priority < element.priority) ||
+                    (swap !== null && rightChild.priority < leftChild.priority)
+                ) {
+                    swap = rightChildIndex;
+                }
+            }
+            if (swap === null) break;
+            this.heap[i] = this.heap[swap];
+            i = swap;
+        }
+        this.heap[i] = element;
+    }
+}
+
+// Usage
+const pq = new PriorityQueue();
+pq.add(new Task(3, "Clear drains"));
+pq.add(new Task(4, "Feed cat"));
+pq.add(new Task(5, "Make tea"));
+pq.add(new Task(1, "Solve RC tasks"));
+pq.add(new Task(2, "Tax return"));
+
+while (!pq.isEmpty()) {
+    console.log(pq.remove().toString());
+}