几种经典排序算法的JS实现

一.冒泡排序

 function BubbleSort(array) {
     var length = array.length;
     for (var i = length - 1; i > 0; i--) { //用于缩小范围
         for (var j = 0; j < i; j++) { //在范围内进行冒泡，在此范围内最大的一个将冒到最后面
             if (array[j] > array[j+1]) {
                 var temp = array[j];
                 array[j] = array[j+1];
                 array[j+1] = temp;
             }
         }
         console.log(array);
         console.log("-----------------------------");
     }
     return array;
 }

 var arr = [10,9,8,7,7,6,5,11,3];
 var result = BubbleSort(arr);
 console.log(result);
 /*
 [ 9, 8, 7, 7, 6, 5, 10, 3, 11 ]
 -----------------------------
 [ 8, 7, 7, 6, 5, 9, 3, 10, 11 ]
 -----------------------------
 [ 7, 7, 6, 5, 8, 3, 9, 10, 11 ]
 -----------------------------
 [ 7, 6, 5, 7, 3, 8, 9, 10, 11 ]
 -----------------------------
 [ 6, 5, 7, 3, 7, 8, 9, 10, 11 ]
 -----------------------------
 [ 5, 6, 3, 7, 7, 8, 9, 10, 11 ]
 -----------------------------
 [ 5, 3, 6, 7, 7, 8, 9, 10, 11 ]
 -----------------------------
 [ 3, 5, 6, 7, 7, 8, 9, 10, 11 ]
 -----------------------------
 [ 3, 5, 6, 7, 7, 8, 9, 10, 11 ]
 */

二.选择排序

 function SelectionSort(array) {
     var length = array.length;
     for (var i = 0; i < length; i++) { //缩小选择的范围
         var min = array[i]; //假定范围内第一个为最小值
         var index = i; //记录最小值的下标
         for (var j = i + 1; j < length; j++) { //在范围内选取最小值
             if (array[j] < min) {
                 min = array[j];
                 index = j;
             }
         }
         if (index != i) { //把范围内最小值交换到范围内第一个
             var temp = array[i];
             array[i] = array[index];
             array[index] = temp;
         }
         console.log(array);
         console.log("---------------------");
     }
     return array;
 }

 var arr = [ 1, 10, 100, 90, 65, 5, 4, 10, 2, 4 ];
 var result = SelectionSort(arr);
 console.log(result);
 /*
 [ 1, 10, 100, 90, 65, 5, 4, 10, 2, 4 ]
 ---------------------
 [ 1, 2, 100, 90, 65, 5, 4, 10, 10, 4 ]
 ---------------------
 [ 1, 2, 4, 90, 65, 5, 100, 10, 10, 4 ]
 ---------------------
 [ 1, 2, 4, 4, 65, 5, 100, 10, 10, 90 ]
 ---------------------
 [ 1, 2, 4, 4, 5, 65, 100, 10, 10, 90 ]
 ---------------------
 [ 1, 2, 4, 4, 5, 10, 100, 65, 10, 90 ]
 ---------------------
 [ 1, 2, 4, 4, 5, 10, 10, 65, 100, 90 ]
 ---------------------
 [ 1, 2, 4, 4, 5, 10, 10, 65, 100, 90 ]
 ---------------------
 [ 1, 2, 4, 4, 5, 10, 10, 65, 90, 100 ]
 ---------------------
 [ 1, 2, 4, 4, 5, 10, 10, 65, 90, 100 ]
 ---------------------
 [ 1, 2, 4, 4, 5, 10, 10, 65, 90, 100 ]
 */

三.插入排序

 function InsertionSort(array) {
     var length = array.length;
     for (var i = 0; i < length - 1; i++) {
         //i代表已经排序好的序列最后一项下标
         var insert = array[i+1];
         var index = i + 1;//记录要被插入的下标
         for (var j = i; j >= 0; j--) {
             if (insert < array[j]) {
                 //要插入的项比它小，往后移动
                 array[j+1] = array[j];
                 index = j;
             }
         }
         array[index] = insert;
         console.log(array);
         console.log("-----------------------");
     }
     return array;
 }

 var arr = [100,90,80,62,80,8,1,2,39];
 var result = InsertionSort(arr);
 console.log(result);
 /*
 [ 90, 100, 80, 62, 80, 8, 1, 2, 39 ]
 -----------------------
 [ 80, 90, 100, 62, 80, 8, 1, 2, 39 ]
 -----------------------
 [ 62, 80, 90, 100, 80, 8, 1, 2, 39 ]
 -----------------------
 [ 62, 80, 80, 90, 100, 8, 1, 2, 39 ]
 -----------------------
 [ 8, 62, 80, 80, 90, 100, 1, 2, 39 ]
 -----------------------
 [ 1, 8, 62, 80, 80, 90, 100, 2, 39 ]
 -----------------------
 [ 1, 2, 8, 62, 80, 80, 90, 100, 39 ]
 -----------------------
 [ 1, 2, 8, 39, 62, 80, 80, 90, 100 ]
 -----------------------
 [ 1, 2, 8, 39, 62, 80, 80, 90, 100 ]
 */

四.希尔排序

 function ShellSort(array) {
     var length = array.length;
     var gap = Math.round(length / 2);
     while (gap > 0) {
         for (var i = gap; i < length; i++) {
             var insert = array[i];
             var index = i;
             for (var j = i; j >= 0; j-=gap) {
                 if (insert < array[j]) {
                     array[j+gap] = array[j];
                     index = j;
                 }
             }
             array[index] = insert;
         }
         console.log(array);
         console.log("-----------------------");
         gap = Math.round(gap/2 - 0.1);
     }
     return array;
 }

 var arr = [ 13, 14, 94, 33, 82, 25, 59, 94, 65, 23, 45, 27, 73, 25, 39, 10 ];
 var result = ShellSort(arr);
 console.log(result);
 /*
 [ 13, 14, 45, 27, 73, 25, 39, 10, 65, 23, 94, 33, 82, 25, 59, 94 ]
 -----------------------
 [ 13, 14, 39, 10, 65, 23, 45, 27, 73, 25, 59, 33, 82, 25, 94, 94 ]
 -----------------------
 [ 13, 10, 39, 14, 45, 23, 59, 25, 65, 25, 73, 27, 82, 33, 94, 94 ]
 -----------------------
 [ 10, 13, 14, 23, 25, 25, 27, 33, 39, 45, 59, 65, 73, 82, 94, 94 ]
 -----------------------
 [ 10, 13, 14, 23, 25, 25, 27, 33, 39, 45, 59, 65, 73, 82, 94, 94 ]
 */

五.归并排序

 function MergeSort(array) {
     var length = array.length;
     if (length <= 1) {
         return array;
     } else {
         var num = Math.ceil(length/2);
         var left = MergeSort(array.slice(0, num));
         var right = MergeSort(array.slice(num, length));
         return merge(left, right);
     }
 }

 function merge(left, right) {
     console.log(left);
     console.log(right);
     var a = new Array();
     while (left.length > 0 && right.length > 0) {
         if (left[0] <= right[0]) {
             var temp = left.shift();
             a.push(temp);
         } else {
             var temp = right.shift();
             a.push(temp);
         }
     }
     if (left.length > 0) {
         a = a.concat(left);
     }
     if (right.length > 0) {
         a = a.concat(right);
     }
     console.log(a);
     console.log("-----------------------------");
     return a;
 }

 var arr = [ 13, 14, 94, 33, 82, 25, 59, 94, 65, 23, 45, 27, 73, 25, 39, 10 ];
 var result = MergeSort(arr);
 console.log(result);
 /*
 [ 13 ]
 [ 14 ]
 [ 13, 14 ]
 -----------------------------
 [ 94 ]
 [ 33 ]
 [ 33, 94 ]
 -----------------------------
 [ 13, 14 ]
 [ 33, 94 ]
 [ 13, 14, 33, 94 ]
 -----------------------------
 [ 82 ]
 [ 25 ]
 [ 25, 82 ]
 -----------------------------
 [ 59 ]
 [ 94 ]
 [ 59, 94 ]
 -----------------------------
 [ 25, 82 ]
 [ 59, 94 ]
 [ 25, 59, 82, 94 ]
 -----------------------------
 [ 13, 14, 33, 94 ]
 [ 25, 59, 82, 94 ]
 [ 13, 14, 25, 33, 59, 82, 94, 94 ]
 -----------------------------
 [ 65 ]
 [ 23 ]
 [ 23, 65 ]
 -----------------------------
 [ 45 ]
 [ 27 ]
 [ 27, 45 ]
 -----------------------------
 [ 23, 65 ]
 [ 27, 45 ]
 [ 23, 27, 45, 65 ]
 -----------------------------
 [ 73 ]
 [ 25 ]
 [ 25, 73 ]
 -----------------------------
 [ 39 ]
 [ 10 ]
 [ 10, 39 ]
 -----------------------------
 [ 25, 73 ]
 [ 10, 39 ]
 [ 10, 25, 39, 73 ]
 -----------------------------
 [ 23, 27, 45, 65 ]
 [ 10, 25, 39, 73 ]
 [ 10, 23, 25, 27, 39, 45, 65, 73 ]
 -----------------------------
 [ 13, 14, 25, 33, 59, 82, 94, 94 ]
 [ 10, 23, 25, 27, 39, 45, 65, 73 ]
 [ 10, 13, 14, 23, 25, 25, 27, 33, 39, 45, 59, 65, 73, 82, 94, 94 ]
 -----------------------------
 [ 10, 13, 14, 23, 25, 25, 27, 33, 39, 45, 59, 65, 73, 82, 94, 94 ]
 */

六.快速排序

 function QuickSort(array) {
     var length = array.length;
     if (length <= 1) {
         return array;
     } else {
         var smaller = [];
         var bigger = [];
         var base = [array[0]];
         for (var i = 1; i < length; i++) {
             if (array[i] <= base[0]) {
                 smaller.push(array[i]);
             } else {
                 bigger.push(array[i]);
             }
         }
         console.log(smaller.concat(base.concat(bigger)));
         console.log("-----------------------");
         return QuickSort(smaller).concat(base.concat(QuickSort(bigger)));
     }
 }

 var arr = [ 8, 10, 100, 90, 65, 5, 4, 10, 2, 4 ];
 var result = QuickSort(arr);
 console.log(result);
 /*
 [ 5, 4, 2, 4, 8, 10, 100, 90, 65, 10 ]
 -----------------------
 [ 4, 2, 4, 5 ]
 -----------------------
 [ 2, 4, 4 ]
 -----------------------
 [ 2, 4 ]
 -----------------------
 [ 10, 10, 100, 90, 65 ]
 -----------------------
 [ 90, 65, 100 ]
 -----------------------
 [ 65, 90 ]
 -----------------------
 [ 2, 4, 4, 5, 8, 10, 10, 65, 90, 100 ]
 */

七.堆排序

 function HeapSort(array) {
     function swap(i,j) {
         var temp = array[i];
         array[i] = array[j];
         array[j] = temp;
     }

     function MaxHeap(start, end) {
         var dad = start;
         var son = dad * 2 + 1;//子节点中的左节点
         if (son >= end)
             return;
         if (son + 1 < end && array[son] < array[son + 1])//比较左右节点的值，选择大的那个
             son++;
         if (array[dad] <= array[son]) {//如果父节点小于子节点时，交换父子内容再继续子节点和孙节点比较
             swap(dad, son);
             MaxHeap(son, end);
         }
     }

     var len = array.length;
     //从最后一个父节点开始创建最大堆
     for (var i = Math.floor(len / 2) - 1; i >= 0; i--) {
         console.log(array);
         MaxHeap(i,len);
         console.log(array);
         console.log("----------------------------------");
     }
     //将最大的交换到最后一个位置；在调整最大堆，直至调整到第一个
     for (var i = len - 1; i > 0; i--) {
         swap(0,i);
         MaxHeap(0,i);
         console.log(array);
         console.log("----------------------------");
     }
     return array;
 }

 var a = [1,2,3,4,5];
 HeapSort(a);
 /*
 [ 1, 2, 3, 4, 5 ]
 [ 1, 5, 3, 4, 2 ]
 ----------------------------------
 [ 1, 5, 3, 4, 2 ]
 [ 5, 4, 3, 1, 2 ]
 ----------------------------------
 [ 4, 2, 3, 1, 5 ]
 ----------------------------
 [ 3, 2, 1, 4, 5 ]
 ----------------------------
 [ 2, 1, 3, 4, 5 ]
 ----------------------------
 [ 1, 2, 3, 4, 5 ]
 ----------------------------
 */

参考资料：

http://wuchong.me/blog/2014/02/09/algorithm-sort-summary/