Submission #1151938

#	Time	Username	Problem	Language	Result	Execution time	Memory
1151938		mingga	Tents (JOI18_tents)	C++20	100 / 100	116 ms	70820 KiB

tents

#include "bits/stdc++.h"

using namespace std;

#define ln "\n"
#define pb push_back
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define int long long
const int mod = 1e9 + 7;
const int inf = 2e18;
const int N = 3005;
int w, h, dp[N][N];

int add(int x, int y) {
    x += y;
    if(x >= mod) x -= mod;
    return x;
}

int mul(int x, int y) {
    x %= mod, y %= mod;
    return (x * y) % mod;
}

int c2(int x) {
    int a = x, b = x - 1;
    if(a % 2) b /= 2;
    else a /= 2;
    return mul(a, b);
}

signed main() {
    cin.tie(0) -> sync_with_stdio(0);
    #define task ""
    if(fopen(task ".INP", "r")) {
        freopen(task ".INP", "r", stdin);
        freopen(task ".OUT", "w", stdout);
    }
    cin >> w >> h;
    dp[0][0] = 1;
    for(int i = 1; i <= w; i++) {
        dp[i][0] = 1;
    }
    for(int i = 1; i <= h; i++) {
        dp[0][i] = 1;
    }
    for(int i = 1; i <= w; i++) {
        for(int j = 1; j <= h; j++) {
            dp[i][j] = add(dp[i][j], dp[i - 1][j]);
            dp[i][j] = add(dp[i][j], mul(dp[i - 1][j - 1], 4 * j));
            if(i > 1) dp[i][j] = add(dp[i][j], mul((i - 1) * j, dp[i - 2][j - 1]));
            if(j > 1) dp[i][j] = add(dp[i][j], mul(c2(j), dp[i - 1][j - 2]));
        }
    }
    cout << (dp[w][h] - 1 + mod) % mod << ln;
    cerr << "\nTime: " << clock() * 1000 / CLOCKS_PER_SEC;
}

Compilation message (stderr)

tents.cpp: In function 'int main()':
tents.cpp:39:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   39 |         freopen(task ".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
tents.cpp:40:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |         freopen(task ".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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