Submission #46561

#	Time	Username	Problem	Language	Result	Execution time	Memory
46561		nickyrio	Tents (JOI18_tents)	C++17	100 / 100	157 ms	71952 KiB

tents

#include <bits/stdc++.h>
#define FOR(i, a, b) for (int i = (a); i <= (b); ++i)
#define FORD(i, a, b) for (int i = (a); i >= (b); --i)
#define REP(i, a) for (int i = 0; i < (a); ++i)
#define DEBUG(x) { cerr << #x << '=' << x << endl; }
#define Arr(a, l, r) { cerr << #a << " = {"; FOR(_, l, r) cerr << ' ' << a[_]; cerr << "}\n"; }
#define N 3030
#define pp pair<int, int>
#define endl '\n'
#define IO ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
#define taskname ""
#define bit(S, i) (((S) >> (i)) & 1)
using namespace std;
const long long MOD = 1e9 + 7;
long long dp[N][N];
void Add(long long &a, long long b) { a += b; if (a >= MOD) a -= MOD; }

void Solve() {
    int m, n;
    cin >> m >> n;
    FOR(i, 0, m) dp[i][0] = 1;
    FOR(i, 0, n) dp[0][i] = 1;
    FOR(i, 1, m) FOR(j, 1, n) {
        // Put no tent at row i
        Add(dp[i][j], dp[i - 1][j]);
        // Put just a tent at row i
        Add(dp[i][j], dp[i - 1][j - 1] * 4ll * j % MOD);
        // Put a tent at row i and another tent at the same column
        if (i > 1) Add(dp[i][j], dp[i - 2][j - 1] * (i - 1) * j % MOD);
        // Put two tent at row i
        if (j > 1) Add(dp[i][j], dp[i - 1][j - 2] * ((j - 1) * j / 2) % MOD); 
    }
    cout << (dp[m][n] - 1 + MOD) % MOD;
}
int main() {
    #ifdef NERO
    freopen("test.inp","r",stdin);
    freopen("test.out","w",stdout);
    double stime = clock();
    #else 
        //freopen(taskname".inp","r",stdin);
        //freopen(taskname".out","w",stdout);
    #endif //NERO
    IO;
    Solve();
    #ifdef NERO
    double etime = clock();
    cerr << "Execution time: " << (etime - stime) / CLOCKS_PER_SEC * 1000 << " ms.\n";
    #endif // NERO
}

• Subtask 1: 48 / 48
• Subtask 2: 52 / 52