tc srm 636 div2 500

100的数据直接暴力就行，想多了。。。

ac的代码：

 #include <iostream>
 #include <cstdio>
 #include <cstring>
 #include <cstdlib>
 #include <cmath>
 #include <algorithm>
 #include <vector>
 #define LL __int64
 const int maxn = +;
 using namespace std;
 int a[maxn], sum;

 class SortishDiv2
 {
 public:
     int ways(int sortedness, vector <int> seq)
     {
         int f[maxn], len, i, j, ans = ;
         int cnt = , x[maxn];
         len = seq.size();
         memset(f, , sizeof(f));
         for(i = ; i < len; i++)
             f[seq[i]] = ;
         for(i = ; i <= len; i++)
             if(f[i]==)
                 x[cnt++] = i;
         sort(x, x+cnt);
         do
         {
             int y = ;
             for(i = ; i < len; i++)
             {
                 if(seq[i]==) a[i] = x[y++];
                 else a[i] = seq[i];
             }
             sum = ;
             for(i = ; i < len; i++)
             for(j = i+; j < len; j++)
             if(a[j]>a[i])
             sum ++;
             if(sum == sortedness) ans ++;
         }
         while (next_permutation(x,x+cnt));  //数字的全排列

         return ans;
     }
 };

 /*int main()
 {
     SortishDiv2 s;
     int i, j, n, y, tmp;
     vector<int>v;
     while(1)
     {
         v.clear();
         cin>>n; cin>>y;
         for(i = 0; i < y; i++)
         {
           cin>>tmp;
           v.push_back(tmp);
         }
         cout<<s.ways(n, v)<<endl;
     }
     return 0;
 }*/