5、【常见算法】从长度为n的数组（元素互不相同）中任意选择m个数的所有组合。

 1 //从长度为n的数组（元素互不相同）中任意选择m个数的所有组合。
 2 
 3 #include <iostream>
 4 #include <vector>
 5 
 6 using namespace std;
 7 
 8 int arr[] = {1,2,3,4,5,6,7,8,9,10};
 9 int len = 10, m = 3;
10 
11 void subArray(int num, vector<int> &vec, int curnum, int id)
12 {
13     int i;
14 
15     if(curnum == num)
16     {
17         static int k = 1;
18         cout << k++ << ": ";
19 
20         for(i = 0; i < vec.size(); i++)
21         {
22             cout << vec[i] << " ";
23         }
24         cout << endl;
25         return;
26     }
27 
28     for(i = id; i < len; i++)
29     {
30         vec.push_back(arr[i]);
31         subArray(num, vec, curnum+1, i+1);
32         vec.pop_back();
33     }
34 }
35 
36 int main()
37 {
38     vector<int> vec;
39     subArray(m, vec, 0, 0);
40     return 0;
41 }