add min-heap-construction question

Author: betomoedano

heaps/min-heap-construction.js

@@ -0,0 +1,69 @@
+class MinHeap {
+    constructor(array) {
+        this.heap = this.buildHeap(array);
+    }
+    
+    buildHeap(array) {
+        const firstParentIdx = Math.floor((array.length - 2) / 2);
+        for(let currentIdx = firstParentIdx; currentIdx >= 0; currentIdx--) {
+            this.siftDown(currentIdx, array.length - 1, array);
+        }
+        return array;
+    }
+    
+    siftDown(currentIdx, endIdx, heap) {
+        let childOneIdx = currentIdx * 2 + 1;
+        while(childOneIdx <= endIdx) {
+            const childTwoIdx = currentIdx * 2 + 2 <= endIdx ? currentIdx * 2 + 2 : -1;
+            let idxToSwap;
+            if(childTwoIdx !== -1 && heap[childTwoIdx] < heap[childOneIdx]) {
+                idxToSwap = childTwoIdx;
+            } else {
+                idxToSwap = childOneIdx;
+            }
+            if(heap[idxToSwap] < heap[currentIdx]) {
+                this.swap(currentIdx, idxToSwap, heap);
+                currentIdx = idxToSwap;
+                childOneIdx = currentIdx * 2 + 1;
+            } else {
+                return;
+            }
+        }
+    }
+    
+    siftUp(currentIdx, heap) {
+        let parentIdx = Math.floo((currentIdx - 1) / 2);
+        while(currentIdx > 0 && heap[currentIdx] < heap[parentIdx]) {
+            this.swap(currentIdx, parentIdx, heap);
+            currentIdx = parentIdx;
+            parentIdx = Math.floor((currentIdx - 1) / 2);
+        }
+    }
+    
+    peek() {
+        return this.heap[0];
+    }
+    
+    remove() {
+        this.swap(0, this.heap.length - 1, this.heap);
+        const valueToRemove = this.heap.pop();
+        this.siftDown(0, this.heap.length - 1, this.heap);
+        return valueToRemove;
+    }
+    
+    insert(value) {
+        this.heap.push(value);
+        this.siftUp(this.heap.length - 1, this.heap);
+    }
+    
+    swap(i, j, heap) {
+        const temp = heap[j];
+        heap[j] = heap[i];
+        heap[i] = temp;
+    }
+}
+
+
+const myHeap = new MinHeap([48, 12, 24, 7, 8, -5, 24, 391, 24, 56, 2, 6, 8, 41]);
+
+console.log(myHeap.remove())