c++ 求数组元素的组合，去重和不去重

#include<cstdlib>
#include<iostream>
#include<vector>
using namespace std;
void print(const vector<int>& vec)
{
    vector<int>::const_iterator iter = vec.begin();
    for(; iter!=vec.end(); iter++)
        cout << *iter << " ";
    cout << endl;
}
void find_combination(int* arr, int num, vector<int>& vec)//不去重的求组合实现
{
    if(num == 0)
    {
        print(vec);
        return;
    }
    if(arr[0] == -1)
        return;
    vec.push_back(arr[0]);
    find_combination(arr+1,num-1,vec);
    vec.pop_back();
    find_combination(arr+1,num,vec);
}
void find_combination2(int* arr,int num, vector<int>& vec)//可以去重，以-1结束。
{
    if(num == 0)
    {
        print(vec);
    　　 return;
    }
    if(arr[0] == -1)
    　　 return;
    vec.push_back(arr[0]);
    find_combination(arr+1,num-1,vec);
    vec.pop_back();
    while(*arr == *(arr+1))
        arr++;
    find_combination(arr+1,num,vec);
}
int compare(const void* a, const void* b)
{
     if(*(int*)a > *(int*)b)
         return 1;
     else
         return *(int*)a < *(int*)b ? -1:0;
}
void combination(int* arr, int len,vector<int>& vec)
{
    if(arr == NULL || len <= 0)
        return;
    for(int i =1; i <= len; i++ )
        find_combination2(arr,i,vec);
}
int main()
{
    vector<int> vec;
//    int arr[] = {1,2,3,-1};
    int arr[] = {4,1,1,-1};
    qsort(arr,3,sizeof(int),compare);
    int len = sizeof(arr) / sizeof(arr[0]);
    combination(arr,len,vec);
    return 0;
}
数组元素的组合c++代码