冒泡排序三种方法

//  1.入门版本
  var arr1 = [9,7,4,5,6];
  for(var j = 0; j < arr1.length-1; j++) {
    for(var i = 0; i < arr1.length-1; i++){
      if(arr1[i] > arr1[i+1]){
        var temp = arr1[i];
        arr1[i]=arr1[i+1];
        arr1[i+1] = temp;
      }
    }
  }
  console.log(arr1);

//  2.升级版
var arr1 = [9,7,4,5,6];
 for(var j = 0; j < arr1.length-1; j++) {
    for(var i = 0; i < arr1.length-1-i; i++){
      if(arr1[i] > arr1[i+1]){
      　　var temp = arr1[i];
      　　arr1[i]=arr1[i+1];
      　　arr1[i+1] = temp;
      }
    }
 }
 console.log(arr1);

//  3.终极版
var arr1 = [9,7,4,5,6];
 for(var j = 0; j < arr1.length-1; j++) {
   var flag = true;
   for(var i = 0; i < arr1.length-1; i++){
      if(arr1[i] > arr1[i+1]){
        var temp = arr1[i];
        arr1[i]=arr1[i+1];
        arr1[i+1] = temp;
        flag = false;
      }
    }
   if(flag) {
     break;
   }
 }
 console.log(arr1);