[NYIST32]组合数（状压，枚举，暴力）

题目链接：http://acm.nyist.edu.cn/JudgeOnline/problem.php?pid=32

求n个数中挑出r个数字的所有情况，最后倒序输出所有情况。

状压枚举所有情况就是了，判断长度是否符合条件。

 /*
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 ┓┏┓┏┓┃キリキリ♂ mind！
 ┛┗┛┗┛┃＼○／
 ┓┏┓┏┓┃ /
 ┛┗┛┗┛┃ノ)
 ┓┏┓┏┓┃
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 ┻┻┻┻┻┻
 */
 #include <algorithm>
 #include <iostream>
 #include <iomanip>
 #include <cstring>
 #include <climits>
 #include <complex>
 #include <fstream>
 #include <cassert>
 #include <cstdio>
 #include <bitset>
 #include <vector>
 #include <deque>
 #include <queue>
 #include <stack>
 #include <ctime>
 #include <set>
 #include <map>
 #include <cmath>
 using namespace std;
 #define fr first
 #define sc second
 #define cl clear
 #define BUG puts("here!!!")
 #define W(a) while(a--)
 #define pb(a) push_back(a)
 #define Rint(a) scanf("%d", &a)
 #define Rll(a) scanf("%I64d", &a)
 #define Rs(a) scanf("%s", a)
 #define Cin(a) cin >> a
 #define FRead() freopen("in", "r", stdin)
 #define FWrite() freopen("out", "w", stdout)
 #define Rep(i, len) for(LL i = 0; i < (len); i++)
 #define For(i, a, len) for(LL i = (a); i < (len); i++)
 #define Cls(a) memset((a), 0, sizeof(a))
 #define Clr(a, x) memset((a), (x), sizeof(a))
 #define Fuint(a) memset((a), 0x7f7f, sizeof(a))
 #define lrt rt << 1
 #define rrt rt << 1 | 1
 #define pi 3.14159265359
 #define RT return
 #define lowbit(x) x & (-x)
 #define onenum(x) __builtin_popcount(x)
 typedef long long LL;
 typedef long double LD;
 typedef unsigned long long Uint;
 typedef pair<LL, LL> pii;
 typedef pair<string, LL> psi;
 typedef map<string, LL> msi;
 typedef vector<LL> vi;
 typedef vector<LL> vl;
 typedef vector<vl> vvl;
 typedef vector<bool> vb;
 
 const int maxn = ;
 
 int a[maxn];
 int t[maxn];
 int n, r, cnt;
 vector<vi> v;
 
 int main() {
     // FRead();
     Rep(i, maxn+) a[i] = i + ;
     while(~scanf("%d%d", &n, &r)) {
         int nn =  << n;
         vi p; v.cl();
         For(i, , nn) {
             cnt = ;
             Rep(j, n) {
                 if(i & ( << j)) t[cnt++] = a[j];
             }
             if(cnt == r) {
                 p.cl();
                 for(int j = cnt - ; j >= ; j--) p.pb(t[j]);
                 v.pb(p);
             }
         }
         sort(v.begin(), v.end());
         for(int i = v.size() - ; i >= ; i--) {
             Rep(j, r) {
                 printf("%d", v[i][j]);
             }
             printf("\n");
         }
     }
     RT ;
 }