python/TangDou/CSP-J/AcWingTraining/T6/TD2.cpp

#include <bits/stdc++.h>
using namespace std;
int n, k, nums[26], sel[26];
bool flag[26];
/*
6 2
1 2 2 3 4 2

1 2
1 3
1 4
2 2
2 3
2 4
3 4
*/
void dfs(int index, int min) {
    if (index == k) {
        for (int i = 0; i < k; i++)
            cout << sel[i] << " ";
        cout << endl;
        return;
    }

    for (int i = min; i <= n; i++) {
        if (nums[i] == nums[i - 1] && !flag[i - 1])
            continue;

        sel[index] = nums[i];
        flag[i] = true;
        dfs(index + 1, i + 1);
        flag[i] = false;
    }
}

int main() {
    cin >> n >> k;
    for (int i = 1; i <= n; i++) cin >> nums[i];
    sort(nums + 1, nums + n + 1);
    dfs(0, 1);
    return 0;
}