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Author: vietnamican

Sorting/HeapSort/NodeJS/heapSort.js

@@ -0,0 +1,48 @@
+addToHeap = (heap, newMember) => {
+    return [...heap, newMember];
+}
+
+heapify = (heap, currentIndex) => {
+    while (true) {
+        // this is heapsort algorithm in array
+        // here is map function from index in arr to node in tree
+        //                        1
+        //                     /     \
+        //                    0       1
+        //                  /   \   /   \
+        //                 0     1 0     1
+        //          array                       tree
+        //              0                          1
+        //              1                         10   = 2
+        //              2                         11   = 3
+        //              3                        100   = 4
+        //              4                        101   = 5
+        //          .....                       ....
+        // so the parentNode of a node is floor of (index/2)
+        let parentNode = Math.floor(currentIndex / 2);
+        if (parentNode !== 0) {
+            // array begin with 0 and tree begin with 1 so we have to sub by 1
+            if (heap[currentIndex-1] > heap[parentNode-1]) {
+                [heap[currentIndex-1], heap[parentNode-1]] = [heap[parentNode-1], heap[currentIndex-1]];
+                currentIndex = parentNode;
+            } else {
+                break;
+            }
+        } else {
+            break;
+        }
+    }
+    return heap;
+}
+
+function main() {
+    let arr = [10, 2, 7, 7, 9, 5, 3, 8, 1, 15];
+    let ans = [];
+    arr.forEach((number, index)=>{
+        ans = addToHeap(ans, number);
+        ans = heapify(ans, index+1);
+    })
+    console.log(ans);
+}
+
+main();