Submission #314311

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
314311	2020-10-19T16:14:18 Z	limabeans	Tents (JOI18_tents)	C++17	100 / 100	538 ms	71160 KB

tents

#include <bits/stdc++.h>
using namespace std;

template<typename T>
void out(T x) { cout << x << endl; exit(0); }
#define watch(x) cout << (#x) << " is " << (x) << endl





using ll = long long;


const int maxn = 3001;
const ll mod = 1e9 + 7;

void add(ll& x, ll y) {
    if (x>=mod) x%=mod;
    if (y>=mod) y%=mod;
    x += y;
    if (x>=mod) x%=mod;
}

int n,m;
ll dp[maxn][maxn];

ll choose2(ll x) {
    return x*(x-1)/2;
}

ll f(int i, int j) {
    if (i==0 || j==0) return 1;
    ll &res = dp[i][j];
    if (~res) return res;
    res = 0;
    add(res, f(i-1,j));
    add(res, 4ll*j*f(i-1,j-1));
    if (j>=2) add(res, choose2(j)*f(i-1,j-2));
    if (i>=2) add(res, 1ll*j*(i-1)*f(i-2,j-1));

    return res;
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0);  cout.tie(0);


    
    cin>>n>>m;
    memset(dp,-1,sizeof(dp));
    ll res = f(n,m);
    res--;
    res%=mod;
    res+=mod;
    res%=mod;
    cout<<res<<endl;    
    return 0;
}

Subtask #1

48.0 / 48.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	42 ms	70776 KB	Output is correct
2	Correct	42 ms	70776 KB	Output is correct
3	Correct	42 ms	70776 KB	Output is correct
4	Correct	43 ms	70784 KB	Output is correct
5	Correct	48 ms	70776 KB	Output is correct
6	Correct	43 ms	70816 KB	Output is correct
7	Correct	42 ms	70784 KB	Output is correct
8	Correct	41 ms	70776 KB	Output is correct
9	Correct	41 ms	70776 KB	Output is correct
10	Correct	43 ms	70776 KB	Output is correct
11	Correct	41 ms	70776 KB	Output is correct
12	Correct	47 ms	70892 KB	Output is correct

Subtask #2

52.0 / 52.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	42 ms	70776 KB	Output is correct
2	Correct	42 ms	70776 KB	Output is correct
3	Correct	42 ms	70776 KB	Output is correct
4	Correct	43 ms	70784 KB	Output is correct
5	Correct	48 ms	70776 KB	Output is correct
6	Correct	43 ms	70816 KB	Output is correct
7	Correct	42 ms	70784 KB	Output is correct
8	Correct	41 ms	70776 KB	Output is correct
9	Correct	41 ms	70776 KB	Output is correct
10	Correct	43 ms	70776 KB	Output is correct
11	Correct	41 ms	70776 KB	Output is correct
12	Correct	47 ms	70892 KB	Output is correct
13	Correct	42 ms	70844 KB	Output is correct
14	Correct	42 ms	70912 KB	Output is correct
15	Correct	329 ms	71160 KB	Output is correct
16	Correct	45 ms	70776 KB	Output is correct
17	Correct	70 ms	70920 KB	Output is correct
18	Correct	104 ms	70904 KB	Output is correct
19	Correct	375 ms	71160 KB	Output is correct
20	Correct	296 ms	71028 KB	Output is correct
21	Correct	188 ms	70904 KB	Output is correct
22	Correct	211 ms	71012 KB	Output is correct
23	Correct	138 ms	71064 KB	Output is correct
24	Correct	538 ms	71160 KB	Output is correct
25	Correct	375 ms	71032 KB	Output is correct
26	Correct	438 ms	71040 KB	Output is correct
27	Correct	497 ms	71032 KB	Output is correct