Heap implementation using typescript

Author: bfar97

heap.ts

@@ -0,0 +1,81 @@
+class Heap {
+    heap: Array<number>
+    constructor(arr: Array<number>) {
+        this.heap = this.buildHeap(arr)
+    }
+
+    private swap(arr: Array<number>, i: number, j: number) {
+        let temp = arr[i]
+        arr[i] = arr[j]
+        arr[j] = temp
+    }
+
+    private buildHeap(arr: Array<number>) {
+        // builds a heap from an array of elements
+        for(let i = Math.floor((arr.length-1)/2); i >= 0; i--) {
+            this.heapify(arr, i)
+        }
+        return arr
+    }
+
+    insert(element: number) {
+        // insert an element into the heap
+        this.heap.push(element)
+        this.heap = this.buildHeap(this.heap)
+    }
+
+    delete(index: number) {
+        // delete an element from the heap
+        this.heap.splice(index, 1)
+        this.heap = this.buildHeap(this.heap)
+    }
+
+    private heapify(arr: Array<number>, index: number) {
+        // used when an inserted element unbalances the heap and it loses the heap properties
+        // bottom-up approach
+        let largest = index
+        let left = this.getLeft(index)
+        let right = this.getRight(index)
+        if ((left <= arr.length) && (arr[left] > arr[index])){
+            largest = left
+        }
+        if ((right <= arr.length) && (arr[right] > arr[largest])){
+            largest = right
+        } 
+        if (largest != index){
+            this.swap(arr, index, largest)
+            this.heapify(arr, largest)
+        }
+    }
+
+    getMax() {
+        // returns the max element in the heap
+        return this.heap[0]
+    }
+
+    pop() {
+        // returns the max element in the heap and deletes it from the heap
+        let max = this.heap[0]
+        this.delete(0)
+        return max
+    }
+
+    private getRight(index: number) {
+        return 2 * index + 2
+    }
+    private getLeft(index: number) {
+        return 2 * index + 1
+    }
+
+    // HEAP SORT
+    heapSort() {
+        // sorts the heap in ascending order
+        let tmp = [...this.heap]
+        let sorted = []
+        while(this.heap.length > 0) {
+            sorted.push(this.pop())
+        }
+        this.heap = tmp
+        return sorted.reverse()
+    }
+}