javascript实现冒泡排序及改进算法

/**
 * Created by kaer on 2017/5/1.
 */

function bubble(a){
    var len = a.length;
    for(var i=0;i<len-1;i++){
        for(var j = 0;j<len-i;j++){
           if(a[j] > a[j+1])
           {
               var tmp = a[j];
               a[j]=a[j+1];
               a[j+1] = tmp;
           }
        }
    }
    return a;
}

console.log(bubble([2,1,3,4,6,5]));

//改进：设置一个标志位，用于标识最后一次交换的位置
function bubble1(a){
    var len = a.length;
    var b =len-1;
    var pos = 0;
    for(var i=0;i<len-1;i++){
        for(var j = 0;j<b;j++){
            if(a[j] > a[j+1])
            {
                var tmp = a[j];
                a[j]=a[j+1];
                a[j+1] = tmp;
                pos = j;
            }
        }
        b = pos;
    }
    return a;
}

console.log(bubble1([2,1,3,4,6,5]));

//改进：一次排序同时找出最大值和最小值，查询次数减少一半

function bubble2(a){
    var high = a.length -1;
    var low = 0;
    while(low < high){
        for(var i=0;i<high;i++){
            if(a[i]>a[i+1]){
                var tmp = a[i];
                a[i]=a[i+1];
                a[i+1] = tmp;
            }
        }
        --high;
        for(var j=high;j>low;j--){
            if(a[j]<a[j-1]){
                var tmp = a[j];
                a[j]=a[j-1];
                a[j-1] = tmp;
            }
        }
        ++low;
    }
    return a;
}

console.log(bubble2([2,1,3,4,6,5]));