归并排序与快速排序比较（JS版)

具体解释看代码，代码如下

//主函数
function main() {
    var quickTimeArray = new Array();
    var mergeTimeArray = new Array();
    for (var i = 1; i <= 20; i++) {


        var array = getRandomArrayEasy(5000*i    );
        var array2 = array.slice(0);


        var startTime = new Date().getTime();
        doMergeSort(array);


        var endTime = new Date().getTime();
        mergeTimeArray.push(endTime - startTime);



        var startTime = new Date().getTime();

        doQuickSort(array2);


        var endTime = new Date().getTime();

        quickTimeArray.push(endTime - startTime);

    }
    draw(quickTimeArray,mergeTimeArray);


}



//归并排序
function doMergeSort(array) {
    mergeSort(array, 0, array.length - 1);
}

function mergeSort(array, low, high) {
    var mid = 0;
    if (low < high) {
        mid = parseInt((low + high) / 2);
        mergeSort(array, low, mid);
        mergeSort(array, mid + 1, high);
        merge(array, low, mid, high);
    }
}

function merge(array, low, mid, high) {
    var tempArray = new Array();
    var i = low;
    var j = mid + 1;
    while (true) {
        var small = 0;
        if (array[i] < array[j]) {
            small = array[i]
            i++;
        } else {
            small = array[j];
            j++;
        }
        tempArray.push(small);
        if (i > mid) {
            //i结束，只需要复制i到j-1就行了
            for (var k = low; k < j; k++) {
                array[k] = tempArray.shift();
            }
            break;
        }
        if (j > high) {
            for (var k = i; k <= mid; k++) {
                tempArray.push(array[k]);
            }
            for (var k = low; k <= high; k++) {
                array[k] = tempArray.shift();
            }
            break;
        }

    }

}

//快速排序
//return 排序好的数组
function doQuickSort(array) {
    quickSort(array, 0, array.length - 1);
}

function quickSort(array, low, high) {
    var w = 0;
    if (low < high) {
        w = split(array, low, high);
        quickSort(array, low, w - 1);
        quickSort(array, w + 1, high);
    }
}

//快速排序的划分算法
//return 划分好的数组
function split(array, low, high) {
    var temp = array[low];
    var temp2 = getSplitingElementIndex(array, low, high);
    array[low] = array[temp2];
    //获得划分元素的位置
    array[temp2] = temp;
    var i = low;
    var x = array[low];
    for (var j = low + 1; j <= high; j++) {
        if (array[j] <= x) {
            i++;
            if (i != j) {
                var temp3 = array[i];
                array[i] = array[j];
                array[j] = temp3;
            }
        }
    }
    var temp4 = array[low];
    array[low] = array[i];
    array[i] = temp4;
    return i;

}

//寻找划分元素
//return 划分元素在数组中的位置
//param array 数组
//param low 下限
//param high 上限
function getSplitingElementIndex(array, low, high) {
    var mid = low + parseInt((low + high) / 2);
    if (array[mid] > array[low])//array[mid] 为第二大时返回mid
    {
        if (array[mid] < array[high]) {
            return mid;
        } else {
            if (array[high] < array[low]) {
                return low;
            } else {
                return high;
            }
        }
    } else {
        if (array[low] < array[high])//array[low] 为第二大是返回low
        {
            return low;
        } else {
            if (array[high] > array[low]) {
                return high;
            } else {
                return low;
            }
        }
    }
}

//size数组大小
//floor数据下限 floor>=0;
//upper数据上限
//return 数组对象
function getRandomArray(size, floor, upper) {
    if (floor < 0 || upper < 0)
        return null;
    var temp = upper - floor;
    var array = new Array();
    for (var i = 0; i < size; i++) {
        array[i] = parseInt(Math.random() * temp + floor);
    }
    return array;

}

//封装好的默认范围为0到100000的getRandomArray
function getRandomArrayEasy(size) {
    return getRandomArray(size, 0, 100000);
}

//画图
function draw(QTArray,MTArray) {
    var quickTr = document.getElementById("quickSort");
    var mergeTr = document.getElementById("mergeSort");
    for(var i=0;i<QTArray.length;i++)
    {
        var th  = document.createElement('th');
        th.innerHTML=QTArray[i];
        quickTr.appendChild(th);

        var th2  = document.createElement('th');
        th2.innerHTML=MTArray[i];
        mergeTr.appendChild(th2);
    }

}

附上调用的页面

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" lang="en">
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <title>index</title>
        <meta name="author" content="Jabba" />
        <!-- Date: 2012-11-15 -->
    </head>
    <body >
        <script type="text/javascript" src="sort.js"></script>
        <div align= "center">
            <input type="button" value="start" onclick="main()"/>
        </div>
        <div align="center">
            <table id="table" rows="3" cols="21" border="1">
                <tr>
                    <th>排序算法</th>
                    <th colspan="20">排序时间(毫秒)</th>
                </tr>
                <tr id="mergeSort">
                    <td>归并排序</td>
                </tr>
                <tr id="quickSort">
                    <td>快速排序</td>
                </tr>
            </table>
        </div>

    </body>

</html>