d3-sort-visualization/js/quicksort.js

/**
 *
 */
var QuickSort = function() {
    this.instructions = [];
    this.swaps = 0;
    this.comparisons = 0;
};

QuickSort.prototype = Object.create(Sorter.prototype);

QuickSort.prototype.instruct = function() {
    this.instructions.push(arguments);
    return this;
};

// NOTE adds to an instruction set
/**
 *
 */
QuickSort.prototype.sort = function(arr, start, end) {
    if (end - start <= 0) {
        this.instruct('highlight', end)
            .instruct('message1', 'Start: ' + start)
            .instruct('message2', 'End: ' + end)
        return arr;
    }

    var left = start;
    var right = end;

    var pivot = Math.floor((right + left) / 2);
    var pivotval = arr[pivot].value;
    var tmp;

    this.instruct('initSection', left, right)
        .instruct('highlight', pivot)
        .instruct('message3', 'Pivot value: ' + pivotval);

    while (left <= right) {
        while (arr[left].value < pivotval) {
            left++;

            this.comparisons++;
            this.instruct('marker1', left, 'Left')
                .instruct('message1', 'Left: ' + left)
                .instruct('stats1', 'Comparisons: ' + this.comparisons)
        }

        while (arr[right].value > pivotval) {
            right--;

            this.comparisons++;
            this.instruct('marker2', right, 'Right')
                .instruct('message2', 'Right: ' + right)
                .instruct('stats1', 'Comparisons: ' + this.comparisons)
        }

        if (left <= right) {
            tmp = arr[left];
            arr[left] = arr[right];
            arr[right] = tmp;

            left++;
            right--;

            this.swaps++;
            this.instruct('swap', left, right)
                .instruct('stats2', 'Swaps: ' + this.swaps)
                .instruct('message1', 'Left: ' + left)
                .instruct('message2', 'Right: ' + right)
                .instruct('marker1', left)
                .instruct('marker2', right);
        }
    }

    this.sort(arr, start, right);
    this.sort(arr, left, end);

    return arr;
};