TopCoder SRM 176 Deranged 夜

代码：

#include<iostream>
#include<cstring>
#include<cstdio>
#include<string>
#include<set>
#include<map>
#include<cmath>
#include<algorithm>
#include<vector>
#include<cmath>
#include<queue>
#include<stack>

//#define ull unsigned long long
#define ll long long

using namespace std;

const int INF=0x3f3f3f3f;

const int MOD=1000003;
const int N=15;
ll dp0[1<<N],dp1[1<<N];
ll factorial[N];
class Deranged
{
    public:
    long long numDerangements(vector <int> nums)
    {
        int n=nums.size();
        memset(dp0,0,sizeof(dp0));
        dp0[(1<<n)-1]=1;
        for(int w=0;w<n;++w)
        {
            memset(dp1,0,sizeof(dp1));
            for(int i=0;i<(1<<n);++i)
            {
                for(int j=0;j<n;++j)
                if((i&(1<<j))&&nums[j]!=nums[w])
                {
                    dp1[i^(1<<j)]+=dp0[i];
                }
            }
            memcpy(dp0,dp1,sizeof(dp0));
        }
        ll sum=dp0[0];
        factorial[0]=1;
        for(int i=1;i<=n;++i)
        factorial[i]=factorial[i-1]*i;
        for(int i=0;i<n;++i)
        {
            int x=0;
            for(int j=0;j<n;++j)
            {
                if(nums[j]==i)
                ++x;
            }
            sum/=factorial[x];
        }
        return sum;
    }
};