1.分治去重（数组去重：一分为二，left递归去重，right递归去重，循环right，如果不在left里，加到left，返回left）
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style></style>
<script>
function findInArray(n,arr){
for(var i = 0; i<arr.length; i++){
if(arr[i]==n){return true;}
}
return false;
}
function removeDup(arr,s,e){
if(s>e){return [];}
else if(s==e){
return [arr[s]];
}
var c = Math.floor((s+e)/2);
var left = removeDup(arr,s,c);
var right = removeDup(arr,c+1,e);
for(var i=0; i<right.length; i++){
if(!findInArray(right[i],left)){
left.push(right[i]);
}
}
return left;
}
var arr = [28,19,48,29,28,18,48];
document.write(removeDup(arr,0,arr.length-1));
</script>
</head>
<body>
</body>
</html>
2.分治找最小（找最小值：一分为二，left=递归左最小，right=递归右最小，比较left和right返回）
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>智能社</title>
<style></style>
<script>
function findMin(arr,s,e){
if(s>e){return false;}
else if (s == e){
return arr[s];
}
var c = Math.floor((s+e)/2);
var left = findMin(arr,s,c);
var right = findMin(arr,c+1,e);
if(left < right){
return left;
}
else{
return right;
}
}
var arr = [28,19,48,29,-39,18,-100];
alert(findMin(arr,0,arr.length-1));
</script>
</head>
<body>
</body>
</html>
3.冒泡排序（比较相领的两个值，如果后面的小于前面的，就交换位置。）
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style></style>
<script>
function bubbleSort(arr){
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 tmp = arr[j];
arr[j] = arr[j+1];
arr[j+1] = tmp;
}
}
}
return arr;
}
var arr=[18,38,29,48,-98,27];
document.write(bubbleSort(arr));
</script>
</head>
<body>
</body>
</html>
4.选择排序（从剩余的数据中，找最小的，放到前面（和当前交换位置）。）
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style></style>
<script>
function selectionSort(arr){
for(var i = 0; i<arr.length; i++){
for(var j = i+1; j<arr.length; j++){
if(arr[i] > arr[j]){
var tmp = arr[j];
arr[j] = arr[i];
arr[i] = tmp;
}
}
}
return arr;
}
var arr=[18,38,29,348,-198,29];
document.write(selectionSort(arr));
</script>
</head>
<body>
</body>
</html>
5.归并排序(分治法，二分法，左边排序自己，右面排序自己，每次比较左右数组第一个，小的扔到新的数组里面。）
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style></style>
<script>
function mergeSort(arr,s,e){
if(s>e){return [];}
else if(s==e){
return [arr[s]];
}
var c = Math.floor((s+e)/ 2);
var left = mergeSort(arr,s,c);
var right = mergeSort(arr,c+1,e);
var result = [];
while(left.length || right.length){
if(left[0] > right[0]){
result.push(right.shift());
}else{
result.push(left.shift());
}
if(left.length==0){
result=result.concat(right);
break;
}
else if(right.length == 0){
result=result.concat(left);
break;
}
}
return result;
}
var arr=[18,38,29,348,-198,29];
document.write(mergeSort(arr,0,arr.length-1));
</script>
</head>
<body>
</body>
</html>
6.快速排序（二分法，中间一刀，两个结果数组，分别放左右，递归调用，连接数组,c=arr.splice(cIndex,1),c[0]是中间数组。）
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style></style>
<script>
function quickSort(arr){
if(arr.length == 0){return [];}
var cIndex = Math.floor(arr.length/2);
var c = arr.splice(cIndex,1);
var left = [];
var right = [];
for(var i = 0; i<arr.length; i++){
if(arr[i]<c[0]){
left.push(arr[i]);
}
else{
right.push(arr[i]);
}
}
return quickSort(left).concat(c,quickSort(right));
}
var arr=[18,38,129,348,-198,209];
document.write(quickSort(arr));
</script>
</head>
<body>
</body>
</html>
