插入排序：
var a = [1,7,4,2,17,13,9]
function insertionSort(arr){
arr.map((d,index)=>{
let i = index
while(d<arr[i-1]&&i-1>0){
[arr[i-1],arr[i]]=[arr[i],arr[i-1]]
i–
}
})
} insertionSort(a)
归并排序（非 hack）
function merge (arr,l,m,r){
var left = []
var right = []
for (let i =l;i<m;i++){
// console.log(i)
left.push(arr[i])
}
for(let j = m;j<=r;j++){
right.push(arr[j])
// console.log(j)
}
left.push(Infinity)
right.push(Infinity)
console.log(left,right)
var i =0
var j =0
for(let k =l;k<r+1;k++){
if(left[i]<right[j]){
arr[k]=left[i]
i++
}else{
arr[k]=right[j]
j++
}
}
} function mergeSort(arr,l,r){
if(r>l){
var m=Math.ceil((l+r)/2)
// console.log(m)
mergeSort(arr,l,m-1)
mergeSort(arr,m,r)
merge(arr,l,m,r)
}
}
归并排序（酷炫简单）
function merge(left, right) {
var tmp = [];
while (left.length && right.length) {
if (left[0] < right[0])
tmp.push(left.shift());
else
tmp.push(right.shift());
}
return tmp.concat(left, right);
}
function mergeSort(a) {
if (a.length === 1)
return a;
var mid = ~~(a.length / 2)
, left = a.slice(0, mid)
, right = a.slice(mid);
return merge(mergeSort(left), mergeSort(right));
}