剪枝YYDS

#include<bits/stdc++.h>
#include<iomanip>
using namespace std;
int n,r;

void DFS(int i,vector<int> z){
    if(i == r){
        for(int j = 0;j < z.size();j ++){
            cout << setw(3) << z[j];
        }
        cout << endl;
        return;
    }
    int tmp2;
    if(z.size() == 0){
        tmp2 = 0;
    } else {
        tmp2 = z[z.size() - 1];
    }
    for(int j = tmp2 + 1;j <= tmp2 + (n - tmp2) - (r - i) + 1;j ++){
        vector<int> tmp = z;
        tmp.push_back(j);
        DFS(i + 1,tmp);
    }
}

int main(){
    cin >> n >> r;
    DFS(0,{});
    return 0;
}