iam-frankqiu / js-algorithms

Some javascript clean code.

js-algorithms

Some algorithms implemented by javascript.

heap sorting

function sort( arr)
{
    var n = arr.length;

    // Build heap (rearrange array)
    for (var i = Math.floor(n / 2) - 1; i >= 0; i--)
        heapify(arr, n, i);

    // One by one extract an element from heap
    for (var i = n - 1; i > 0; i--) {
        // Move current root to end
        var temp = arr[0];
        arr[0] = arr[i];
        arr[i] = temp;

        // call max heapify on the reduced heap
        heapify(arr, i, 0);
    }
}

// To heapify a subtree rooted with node i which is
// an index in arr[]. n is size of heap
function heapify(arr, n, i)
{
    var largest = i; // Initialize largest as root
    var l = 2 * i + 1; // left = 2*i + 1
    var r = 2 * i + 2; // right = 2*i + 2

    // If left child is larger than root
    if (l < n && arr[l] > arr[largest])
        largest = l;

    // If right child is larger than largest so far
    if (r < n && arr[r] > arr[largest])
        largest = r;

    // If largest is not root
    if (largest != i) {
        var swap = arr[i];
        arr[i] = arr[largest];
        arr[largest] = swap;

        // Recursively heapify the affected sub-tree
        heapify(arr, n, largest);
    }
}