Quick sort merge sort

. 1 #include <the iostream>
 2 #include <Vector>
 . 3 #include <algorithm>
 . 4  
. 5  the using  namespace STD;
 . 6  
. 7  void quicksort (Vector < int > & A, int L, int R & lt) {
 . 8      // recursive outlet 
. 9      IF (L> = R & lt) return ;
 10      // the left and right borders define two pointers, pointers left in the i <= target, the right pointer j> = target 
. 11      int I = L - . 1 , j = R & lt + . 1 ;   
 12 is      // target current interval as [l, r] in any of a number, generally selected from l, r, l + r >> 2, the position of the random value
13 is      int target A = [L + R & lt >> . 1 ];
 14      // implemented here left pointer i <= target, j right pointer> = target, the termination condition is not met even pointer 
15      the while (i < J) {
 16          // long as even a number of pointers to meet the condition is not satisfied, the stop position number, otherwise continue to walk 
. 17          do ++ I; the while (a [I] < target);
 18 is          do --j; the while (a [j]> target);
 . 19          // implemented here the exchange, because certain number satisfying> i position = target, j empathy same position, so They exchange, so that the number they want respectively 
20 is          IF ( I < J) the swap (a [I], a [J]);
 21 is      }
 22 is      // to sort recursive had been properly arranged two sections 
23     quicksort(a,l,j);
24     quicksort(a,j+1,r);
25 }
26 
27 int main(){
28     int n;
29     cin >> n;    
30     vector<int> a(n,0);
31     for(int i = 0;i < a.size();++i)cin>>a[i];
32     quicksort(a,0,a.size()-1);
33     for(int i = 0;i < a.size();++i)cout << a[i] << " ";
34     return 0;
35 }