void quick(int* arr,int start,int end)
{
int left = start;
int right = end;
int mid = arr[start];
while(left < right)
{
while(left < right)
{
if (arr[right] < mid)
{
arr[left++] = arr[right];
break;
}
right--;
}
while(left < right)
{
if (arr[left] > mid)
{
arr[right--] = arr[left];
break;
}
left++;
}
}
arr[left] = mid;
if (left > start)
quick(arr,start,left-1);
if (right < end)
quick(arr,right+1,end);
}