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名词解释
n: 数据规模
k:“桶”的个数
In-place: 占用常数内存，不占用额外内存
Out-place: 占用额外内存
稳定性：排序后2个相等键值的顺序和排序之前它们的顺序相同
10
var a = [3,44,38,5,47,15,36,26,27,2,46,4,19,50,48]
冒泡排序（Bubble Sort）
function bubbleSort(arr) {
var len = arr.length;
for (var i = 0; i < len; i++) {
for (var j = 0; j < len - 1 - i; j++) {
if (arr[j] > arr[j + 1]) { //相邻元素两两对比
var temp = arr[j + 1]; //元素交换
arr[j + 1] = arr[j];
arr[j] = temp;
}
}
}
return arr;
}
选择排序（Selection Sort）
function selectionSort(arr) {
var len = arr.length;
var minIndex, temp;
for (var i = 0; i < len - 1; i++) {
minIndex = i;
for (var j = i + 1; j < len; j++) {
if (arr[j] < arr[minIndex]) { //寻找最小的数
minIndex = j; //将最小数的索引保存
}
}
temp = arr[i];
arr[i] = arr[minIndex];
arr[minIndex] = temp;
}
return arr;
}
插入排序（Insertion Sort）
function insertionSort(arr) {
var len = arr.length;
var preIndex, current;
for (var i = 1; i < len; i++) {
preIndex = i - 1;
current = arr[i];
while (preIndex >= 0 && arr[preIndex] > current) {
arr[preIndex + 1] = arr[preIndex];
preIndex--;
}
arr[preIndex + 1] = current;
}
return arr;
}
希尔排序（Shell Sort）
function shellSort(arr) {
var len = arr.length,
temp,
gap = 1;
while (gap < len / 3) { //动态定义间隔序列
gap = gap * 3 + 1;
}
for (gap; gap > 0; gap = Math.floor(gap / 3)) {
for (var i = gap; i < len; i++) {
temp = arr[i];
for (var j = i - gap; j >= 0 && arr[j] > temp; j -= gap) {
arr[j + gap] = arr[j];
}
arr[j + gap] = temp;
}
}
return arr;
}
归并排序（Merge Sort）
function mergeSort(arr) { //采用自上而下的递归方法
var len = arr.length;
if (len < 2) {
return arr;
}
var middle = Math.floor(len / 2),
left = arr.slice(0, middle),
right = arr.slice(middle);
return merge(mergeSort(left), mergeSort(right));
}
function merge(left, right) {
var result = [];
while (left.length && right.length) {
if (left[0] <= right[0]) {
result.push(left.shift());
} else {
result.push(right.shift());
}
}
while (left.length)
result.push(left.shift());
while (right.length)
result.push(right.shift());
return result;
}
快速排序（Quick Sort）
function quickSort(arr, left, right) {
var len = arr.length,
partitionIndex,
left = typeof left != 'number' ? 0 : left,
right = typeof right != 'number' ? len - 1 : right;
if (left < right) {
partitionIndex = partition(arr, left, right);
quickSort(arr, left, partitionIndex - 1);
quickSort(arr, partitionIndex + 1, right);
}
return arr;
}
function partition(arr, left, right) { //分区操作
var pivot = left, //设定基准值（pivot）
index = pivot + 1;
for (var i = index; i <= right; i++) {
if (arr[i] < arr[pivot]) {
swap(arr, i, index);
index++;
}
}
swap(arr, pivot, index - 1);
return index - 1;
}
function swap(arr, i, j) {
var temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
堆排序（Heap Sort）
var len; //因为声明的多个函数都需要数据长度，所以把len设置成为全局变量
function buildMaxHeap(arr) { //建立大顶堆
len = arr.length;
for (var i = Math.floor(len / 2); i >= 0; i--) {
heapify(arr, i);
}
}
function heapify(arr, i) { //堆调整
var left = 2 * i + 1,
right = 2 * i + 2,
largest = i;
if (left < len && arr[left] > arr[largest]) {
largest = left;
}
if (right < len && arr[right] > arr[largest]) {
largest = right;
}
if (largest != i) {
swap(arr, i, largest);
heapify(arr, largest);
}
}
function swap(arr, i, j) {
var temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
function heapSort(arr) {
buildMaxHeap(arr);
for (var i = arr.length - 1; i > 0; i--) {
swap(arr, 0, i);
len--;
heapify(arr, 0);
}
return arr;
}
计数排序（Counting Sort）
function countingSort(arr, maxValue) {
var bucket = new Array(maxValue + 1),
sortedIndex = 0;
arrLen = arr.length,
bucketLen = maxValue + 1;
for (var i = 0; i < arrLen; i++) {
if (!bucket[arr[i]]) {
bucket[arr[i]] = 0;
}
bucket[arr[i]]++;
}
for (var j = 0; j < bucketLen; j++) {
while (bucket[j] > 0) {
arr[sortedIndex++] = j;
bucket[j]--;
}
}
return arr;
}
桶排序（Bucket Sort）
function bucketSort(arr, bucketSize) {
if (arr.length === 0) {
return arr;
}
var i;
var minValue = arr[0];
var maxValue = arr[0];
for (i = 1; i < arr.length; i++) {
if (arr[i] < minValue) {
minValue = arr[i]; //输入数据的最小值
} else if (arr[i] > maxValue) {
maxValue = arr[i]; //输入数据的最大值
}
}
//桶的初始化
var DEFAULT_BUCKET_SIZE = 5; //设置桶的默认数量为5
bucketSize = bucketSize || DEFAULT_BUCKET_SIZE;
var bucketCount = Math.floor((maxValue - minValue) / bucketSize) + 1;
var buckets = new Array(bucketCount);
for (i = 0; i < buckets.length; i++) {
buckets[i] = [];
}
//利用映射函数将数据分配到各个桶中
for (i = 0; i < arr.length; i++) {
buckets[Math.floor((arr[i] - minValue) / bucketSize)].push(arr[i]);
}
arr.length = 0;
for (i = 0; i < buckets.length; i++) {
insertionSort(buckets[i]); //对每个桶进行排序，这里使用了插入排序
for (var j = 0; j < buckets[i].length; j++) {
arr.push(buckets[i][j]);
}
}
return arr;
}
基数排序（Radix Sort）
var counter = [];
function radixSort(arr, maxDigit) {
var mod = 10;
var dev = 1;
for (var i = 0; i < maxDigit; i++, dev *= 10, mod *= 10) {
for (var j = 0; j < arr.length; j++) {
var bucket = parseInt((arr[j] % mod) / dev);
if (counter[bucket] == null) {
counter[bucket] = [];
}
counter[bucket].push(arr[j]);
}
var pos = 0;
for (var j = 0; j < counter.length; j++) {
var value = null;
if (counter[j] != null) {
while ((value = counter[j].shift()) != null) {
arr[pos++] = value;
}
}
}
}
return arr;
}