归并排序-algorithms_3th

 1 #include <iostream>
 2 #include <iterator>
 3 #include <vector>
 4 using namespace std;
 5 
 6 void displayArray(int* const,const int&);
 7 void displayVec(vector<int> &);
 8 
 9 void MERGE(int * const A,const int &p,const int &q,const int &r){
10     vector<int> L;
11     for (int i = p; i <= q; ++i){
12         L.push_back(A[i]);
13     }
14     vector<int> R;
15     for (int i = q + 1; i <= r; ++i){
16         R.push_back(A[i]);
17     }
18 
19     auto i = L.begin();
20     auto j = R.begin();
21     for (int k = p; k <= r; ++k){
22         if (i != L.end() && j != R.end()){
23             if (*i <= *j){
24                 A[k] = *i;
25                 ++i;
26             }
27             else{
28                 A[k] = *j;
29                 ++j;
30             }
31         }
32         else{
33             if (i == L.end()){
34                 A[k] = *j;
35                 ++j;
36             }
37             else{
38                 A[k] = *i;
39                 ++i;
40             }
41         }
42     }
43 }
44 
45 void MERGE_SORT(int *const A,const int &p,const int &r){
46     if (p < r){
47         int q = (p + r) / 2;
48         MERGE_SORT(A, p, q);
49         MERGE_SORT(A, q + 1, r);
50         MERGE(A, p, q, r);
51     }
52 }
53 
54 void displayArray(int * const a,const int &length){
55     for (int i = 0; i < length; ++i){
56         cout << " " << a[i];
57     }
58     cout << endl;
59 }
60 
61 int main(void)
62 {
63     int a[] = {2,6,21,7,3,2,76,23,8,31,45,1,42,1,57,2,241,3};
64     MERGE_SORT(a, 0, end(a)-begin(a)-1);
65     displayArray(a, end(a)-begin(a));
66     system("pause");
67     return 0;
68 }