Submission #1055049

#	Time	Username	Problem	Language	Result	Execution time	Memory
1055049		manhlinh1501	Tents (JOI18_tents)	C++17	100 / 100	152 ms	71344 KiB

tents

#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
const int MAXN = 3e3 + 5;
const i64 MOD = 1e9 + 7;

int N, M;

i64 dp[MAXN][MAXN];

i64 MUL(i64 a, i64 b) {
    return (a * b) % MOD;
}

i64 ADD(i64 a, i64 b) {
    return (a + b) % MOD;
}

i64 calc(int r, int c) {
    if(r < 0 or c < 0) return 0;
    if(r == 0 or c == 0) return 1;
    i64 &res = dp[r][c];
    if(res != -1) return res;
    res = 0;
    res = ADD(res, MUL(c * (c - 1) / 2, calc(r - 1, c - 2)));
    res = ADD(res, calc(r - 1, c));
    res = ADD(res, MUL(4 * c, calc(r - 1, c - 1)));
    res = ADD(res, MUL(c * (r - 1), calc(r - 2, c - 1)));
    return res;
}

signed main() {
#define TASK "code"

    if (fopen(TASK ".inp", "r")) {
        freopen(TASK ".inp", "r", stdin);
        freopen(TASK ".out", "w", stdout);
    }

    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    cin >> N >> M;
    memset(dp, -1, sizeof dp);
    cout << (calc(N, M) - 1 + MOD) % MOD;
    return (0 ^ 0);
}

Compilation message (stderr)

tents.cpp: In function 'int main()':
tents.cpp:36:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |         freopen(TASK ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
tents.cpp:37:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |         freopen(TASK ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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