C++ 組み合わせ列挙

#include <vector>
using namespace std;

vector<int> next_comb(int n, int k, vector<int> v){

    for(int i = k-1; i >= 0; --i){
        if (v[i] != i+n-k){
            int t = ++v[i];
            for (int j = i+1; j < k; ++j){
                v[j] = ++t;
            }
            return v;
        }
    }

    for (int i = 0; i < k; ++i){
        v[i] = i;
    }
    return v;
}

vector<int> v = {0, 1, 2};
for (int i = 0; i < 10; ++i){
    for (int j = 0; j < 3; ++j){
        cout << v[j];
    }
    cout << endl;
    v = next_comb(5, 3, v);
}

/*
012
013
014
023
...
234
*/