JS实现排序算法

代码如下：

1、冒泡排序

 <script>
     var arr = [9, 8, 7, 5, 7, 1, 45, 12, 7, 74, 4];
     for (var i = 0; i < arr.length; i++) {
         for (var j = 0; j < arr.length - i - 1; j++) {
             if (arr[j] > arr[j + 1]) {
                 var temp=arr[j];
                 arr[j]=arr[j+1];
                 arr[j+1]=temp;
             }
         }
     }
     console.log(arr);
 </script>

2、选择排序

 <script>
     var arr = [9, 8, 7, 5, 7, 1, 45, 12, 7, 74, 4];
     for (var i = 0; i < arr.length - 1; i++) {
         for (var j = i + 1; j < arr.length; j++) {
             if (arr[i] > arr[j]) {
                 var temp = arr[j];
                 arr[j] = arr[i];
                 arr[i] = temp;
             }
         }
     }
     console.log(arr);
 </script>

3、快速排序

 <script>
     var arr = [9, 8, 7, 5, 7, 1, 45, 12, 7, 74, 4];

     function quickSort(arr) {
         // 递归停止条件
         if (arr.length <= 1) {
             return arr;
         }
         var midIndex = parseInt(arr.length / 2);
         var left = [];
         var right = [];
         arr.forEach(function (item, index) {
             if (index == midIndex) {

             } else if (arr[index] < arr[midIndex]) {
                 left.push(arr[index]);
             } else {
                 right.push(arr[index]);
             }
         });
         return quickSort(left).concat(arr[midIndex]).concat(quickSort(right));
     }
     console.log(quickSort(arr));
 </script>

 4、插入排序

<script>
    var arr = [9, 8, 7, 5, 7, 1, 45, 12, 7, 74, 4];

    for (var i = 0; i < arr.length; i++) {
        var m=i;
        while (i - 1 >= 0 && arr[m] < arr[m - 1]) {
            var temp=arr[m];
            arr[m]=arr[m-1];
            arr[m-1]=temp;
            m--;
        }
    }
    console.log(arr);
</script>

 5、希尔排序

 <script>
     var arr = [9, 8, 7, 5, 7, 1, 45, 12, 7, 74, 4];
     //设定步长初始值
     var interval = parseInt(arr.length / 2);
     while (interval > 0) {
         for (var i = 0; i < arr.length; i++) {
             var m = i;
             while (i - 1 >= 0 && arr[m] < arr[m - interval]) {
                 var temp = arr[m];
                 arr[m] = arr[m - interval];
                 arr[m - interval] = temp;
                 m--;
             }
         }
         interval = parseInt(interval / 2);
     }
     console.log(arr);
 </script>