Submission #59590

#	TimeUTC-0	Username	Problem	Language	Result	Execution time	Memory
59590	2018-07-22 14:33:11	theknife2001	Tents (JOI18_tents)	C++17	100 / 100	1047 ms	71688 KiB

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#include <bits/stdc++.h>
using namespace std;
const int N=3005;
long long dp[N][N];
int n,m;
long long mod=1e9+7;
long long bt(int i, int j)
{
    if(i==n)
    {
        if(j==m)
            return 0;
        return 1;
    }
    if(dp[i][j]!=-1)
        return dp[i][j];
    long long x=bt(i+1,j);
    x%=mod;
    if(j)
        x+=bt(i+1,j-1)*4*j;
    x%=mod;
    if(j&&i+2<=n)
        x+=bt(i+2,j-1)*j*(n-i-1);
    x%=mod;
    if(j>1)
        x+=((bt(i+1,j-2)*j*(j-1))/2)%mod;
    x%=mod;
 
 
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• Subtask 1: 48 / 48
• Subtask 2: 52 / 52