#include <iostream>
#include <vector>

using namespace std;

// 计算阶乘
int factorial(int n) {
    int result = 1;
    for (int i = 1; i <= n; i++) {
        result *= i;
    }
    return result;
}

// 计算组合数方案数
int combination(int n, int k) {
    int numerator = factorial(n);
    int denominator = factorial(k) * factorial(n - k);
    return numerator / denominator;
}

// 输出每一个组合方案
void printCombination(vector<int>& combination) {
    for (int num : combination) {
        cout << num << " ";
    }
    cout << endl;
}

// 递归生成组合方案
void generateCombination(vector<int>& nums, vector<int>& combination, int start, int k) {
    if (k == 0) {
        printCombination(combination);
        return;
    }

    for (int i = start; i < nums.size(); i++) {
        combination.push_back(nums[i]);
        generateCombination(nums, combination, i + 1, k - 1);
        combination.pop_back();
    }
}

// 求解组合数方案数并输出每一个方案
void solveCombination(int n, int k) {
    vector<int> nums;
    for (int i = 1; i <= n; i++) {
        nums.push_back(i);
    }

    vector<int> combination;
    generateCombination(nums, combination, 0, k);
}

int main() {
    int n, k;
    cout << "请输入总数n和选择的个数k：" << endl;
    cin >> n >> k;

    int result = combination(n, k);
    cout << "组合数方案数为：" << result << endl;

    cout << "每一个组合方案为：" << endl;
    solveCombination(n, k);

    return 0;
}