Submission #1256679

#	Time	Username	Problem	Language	Result	Execution time	Memory
1256679		nanaseyuzuki	Tents (JOI18_tents)	C++20	100 / 100	168 ms	71304 KiB

tents

#include <bits/stdc++.h>
/*
    --> Author: Kazuki_Hoshino__8703 <--
    I love Nanasaki Ai ☆*: .。. o(≒＿≒)o .。.:☆
*/
#define fi first
#define se second
#define pii pair<int, int>
#define int long long
using namespace std;

const int mn = 3e3 + 5, bm = (1 << 11) + 1, mod = 1e9 + 7, offset = 5e4;
const int inf = 1e9, base = 311;

int H, W, dp[mn][mn];

int f(int i, int j){
    if(dp[i][j] != -1) return dp[i][j];
    if(i <= 0 || j <= 0) return 1;
    dp[i][j] = 0;
    // dp[i][j] : xét hàng thứ i và còn j hàng chưa sử dụng
    if(j >= 2) dp[i][j] += f(i - 1, j - 2) * j * (j - 1) / 2;
    dp[i][j] %= mod;

    if(i >= 2) dp[i][j] += f(i - 2, j - 1) * (i - 1) * j;
    dp[i][j] %= mod;

    dp[i][j] += f(i - 1, j - 1) * j * 4;
    dp[i][j] %= mod;

    dp[i][j] += f(i - 1, j);
    dp[i][j] %= mod;

    return dp[i][j];
}

void solve(){
    cin >> H >> W;
    memset(dp, -1, sizeof(dp));
    cout << f(H, W) - 1 << '\n';
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    if(fopen("ROBOT.INP", "r")) {
        freopen("ROBOT.INP", "r", stdin);
        freopen("ROBOT.OUT", "w", stdout);
    }
    int t = 1;
    // cin >> t;
    while(t--) {
        solve();
    }
}

Compilation message (stderr)

tents.cpp: In function 'int main()':
tents.cpp:47:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |         freopen("ROBOT.INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
tents.cpp:48:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |         freopen("ROBOT.OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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