排序：冒泡和改进

//冒泡排序
function bubble_sort(array){
    var arr = array.concat();
    var len = arr.length;
    for(var i = len; i > 0; i--){
        var key = 0;
        while(key < i){
            if(arr[key] > arr[key+1]){
                var temp = arr[key];
                arr[key] = arr[key+1];
                arr[key+1] = temp;
            }
            key++;
        }
    }
    alert(arr);
}
//改进1：没有发生交换则代表排序完成
function bubble_sort_1(array){
    var arr = array.concat();
    var len = arr.length;
    var flag;
    for(var i = len; i > 0; i--){
        var key = 0;
        flag = 0;
        while(key < i){
            if(arr[key] > arr[key+1]){
                var temp = arr[key];
                arr[key] = arr[key+1];
                arr[key+1] = temp;
                flag = 1;
            }
            key++;
        }
        if(flag == 0){break;}
    }
    alert(arr);
}
//改进：一趟同时冒泡大小两种
function bubble_sort_2(array){
    var arr = array.concat();
    var len = arr.length;
    var front = 0;
    var back = len - 1;
    while(front < back){
        for(var i = front; i < back; i++){
            if(arr[i] > arr[i+1]){
                var temp = arr[i];
                arr[i] = arr[i+1];
                arr[i+1] = temp;
            }
        }
        back--;
        for(var j = back; j >= 0; j--){
            if(arr[j-1] > arr[j]){
                var temp = arr[j];
                arr[j] = arr[j-1];
                arr[j-1] = temp;
            }
        }
        front++;
    }
    alert(arr);
}