常见排序算法（上）

 1 //1. 冒泡排序
 2 var bubbleSort = function(arr) {
 3     for (var i = 0; i < arr.length; i++) {
 4         var flag = true;
 5         for (var j = 0; j < arr.length - i - 1; j++) {
 6             if (arr[j] > arr[j + 1]) {
 7                 flag = false;
 8                 arraySwap(arr, j, j + 1);
 9             }
10         }
11         if (flag) {
12             break;
13         }
14     }
15     return arr;
16 };
17 
18 //2. 选择排序
19 var selectionSort = function(arr) {
20     for (var i = 1; i < arr.length - 1; i++) {
21         var min = arr[i],
22             minIndex = i;
23         for (var j = i + 1; j < arr.length; j++) {
24             if (arr[j] < min) {
25                 min = arr[j];
26                 minIndex = j;
27             }
28         }
29         arraySwap(arr, i, minIndex);
30     }
31     return arr;
32 };
33 
34 //3. 插入排序
35 var insertionSort = function(arr) {
36     for (var i = 1; i < arr.length; i++) {
37         var temp = arr[i],
38             j = i - 1;
39         while (temp < arr[j] && j > -1) {
40             arr[j + 1] = arr[j];
41             j--;
42         }
43         arr[j + 1] = temp;
44     }
45     return arr;
46 };
47 
48 //4. 快速排序
49 var quickSort = function(arr, start, end) {
50     if (start >= end) {
51         return arr;
52     }
53     var index = partition(arr, start, end);
54     quickSort(arr, start, index - 1);
55     quickSort(arr, index + 1, end);
56     return arr;
57 };
58 
59 var partition = function(arr, start, end) {
60     var temp = arr[start];
61 
62     while (start < end) {
63         while (start < end && arr[end] >= temp) {
64             end--;
65         }
66         arr[start] = arr[end];
67 
68         while (start < end && arr[start] <= temp) {
69             start++;
70         }
71         arr[end] = arr[start];
72     }
73 
74     arr[start] = temp;
75     return start;
76 };