tc srm 636 div2 500

100的数据直接暴力就行，想多了。。。

ac的代码：

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cstdlib>
 5 #include <cmath>
 6 #include <algorithm>
 7 #include <vector>
 8 #define LL __int64
 9 const int maxn = 100+10;
10 using namespace std;
11 int a[maxn], sum;
12
13 class SortishDiv2
14 {
15 public:
16     int ways(int sortedness, vector <int> seq)
17     {
18         int f[maxn], len, i, j, ans = 0;
19         int cnt = 0, x[maxn];
20         len = seq.size();
21         memset(f, 0, sizeof(f));
22         for(i = 0; i < len; i++)
23             f[seq[i]] = 1;
24         for(i = 1; i <= len; i++)
25             if(f[i]==0)
26                 x[cnt++] = i;
27         sort(x, x+cnt);
28         do
29         {
30             int y = 0;
31             for(i = 0; i < len; i++)
32             {
33                 if(seq[i]==0) a[i] = x[y++];
34                 else a[i] = seq[i];
35             }
36             sum = 0;
37             for(i = 0; i < len; i++)
38             for(j = i+1; j < len; j++)
39             if(a[j]>a[i])
40             sum ++;
41             if(sum == sortedness) ans ++;
42         }
43         while (next_permutation(x,x+cnt));  //数字的全排列
44
45         return ans;
46     }
47 };
48
49 /*int main()
50 {
51     SortishDiv2 s;
52     int i, j, n, y, tmp;
53     vector<int>v;
54     while(1)
55     {
56         v.clear();
57         cin>>n; cin>>y;
58         for(i = 0; i < y; i++)
59         {
60           cin>>tmp;
61           v.push_back(tmp);
62         }
63         cout<<s.ways(n, v)<<endl;
64     }
65     return 0;
66 }*/