제출 #1283734

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1283734		nqc	Tents (JOI18_tents)	C++20	48 / 100	221 ms	216272 KiB

tents

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

#define fi first
#define se second
#define ll long long
#define ull unsigned long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pli pair<ll, int>
#define debug(x) cout << #x << " = " << x << '\n'
#define all(a) a.begin(), a.end()
#define SZ(a) (int)(a).size()

const int N = 3e2 + 5;
const int mod = 1e9 + 7;
const ll inf64 = 3e18;
const int inf32 = 2e9 + 5;

ll add(ll a, ll b) {
    a += b;
    if(a < 0) a += mod;
    if(a >= mod) a -= mod;
    return a;
}
ll mul(ll a, ll b) { return a * b % mod; }

int n, m;
ll dp[N][N][N], pw4[N];

void solve() {
    cin >> n >> m;

    pw4[0] = 1;
    for(int i = 1; i <= m; i++) 
        pw4[i] = mul(pw4[i - 1], 4);

    // dp[1][1][0] = m * 4;
    // dp[1][0][2] = m * (m - 1) / 2;
    // for(int i = 1; i < n; i++) {
    //     for(int open = 0; open <= m; open++) {
    //         for(int close = 0; close + open <= m; close++) {
    //             dp[i + 1][open][close] = add(dp[i + 1][open][close], dp[i][open][close]);

    //             // dat vao dong i+1 1 cai leu
    //             // dat vao o trong -> open+1
    //             dp[i + 1][open + 1][close] = add(dp[i + 1][open + 1][close], mul(mul(dp[i][open][close], m - open - close), 4));
    //             // dat vao o open -> open-1, close+1
    //             dp[i + 1][open][close + 1] = add(dp[i + 1][open][close + 1], mul(dp[i][open][close], m - open - close));
                
    //             // dat vao dong i+1 2 cai leu 
    //             // chi dat vao cac o trong -> close + 2
    //             ll tmp = (m - open - close) * (m - open - close - 1) / 2;
    //             dp[i + 1][open][close + 2] = add(dp[i + 1][open][close + 2], mul(dp[i][open][close], tmp)); 
    //         }
    //     }
    // }

    dp[0][0][0] = 1;
    for(int i = 1; i <= n; i++) {
        for(int open = 0; open <= m; open++) {
            for(int close = 0; open + close <= m; close++) {
                dp[i][open][close] = add(dp[i][open][close], dp[i - 1][open][close]);

                // dat vao dong i 1 cai leu 
                // dat vao o trong
                if(open > 0) {
                    dp[i][open][close] = add(dp[i][open][close], mul(dp[i - 1][open - 1][close], m - (open - 1) - close));
                }
                // dat vao o open <=> dat vao cot trong 2 phan tu
                if(open < m && close > 0) {
                    dp[i][open][close] = add(dp[i][open][close], mul(dp[i - 1][open + 1][close - 1], open + 1));
                }

                // dat vao dong i 2 leu 
                // chi dat vao o trong
                if(close >= 2) {
                    ll tmp = (m - open - (close - 2)) * (m - open - (close - 2) - 1) / 2;
                    dp[i][open][close] = add(dp[i][open][close], mul(dp[i - 1][open][close - 2], tmp));
                }
            }
        }
    }

    ll ans = 0;
    for(int open = 0; open <= m; open++) {
        for(int close = 0; close <= m && open + close <= m; close++) 
            ans = add(ans, mul(dp[n][open][close], pw4[open]));
    }
    cout << add(ans, -1) << '\n';
}

int main() {
    auto start = chrono::steady_clock::now();

    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if(fopen("input.txt", "r")) {
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    }
    int test = 1; 
    // cin >> test;
    while(test--) solve();
    
    chrono::duration<double> elapsed {chrono::steady_clock::now() - start};
    cerr << "\n>> Runtime: " << elapsed.count() << "s\n";
}

컴파일 시 표준 에러 (stderr) 메시지

tents.cpp: In function 'int main()':
tents.cpp:98:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   98 |         freopen("input.txt", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
tents.cpp:99:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   99 |         freopen("output.txt", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 48 / 48
• Subtask 2: 0 / 52