Submission #1186917

#	Time	Username	Problem	Language	Result	Execution time	Memory
1186917		monaxia	Tents (JOI18_tents)	C++20	100 / 100	84 ms	35512 KiB

tents

#include <bits/stdc++.h>
#define pb push_back
#define ppb pop_back
#define fr first
#define sc second
#define all(v) v.begin(), v.end()
#define eps (long long)(1e-9)
#define vektor vector

using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;

const ull Mod = 1e9 + 7;
const ll LIMIT = 2e5;
const ll INF = 1e18;
const ld pi = 3.14159265358979323846;

void add(int& a, ll b){
    b %= Mod;
    a %= Mod;

    (a += b) %= Mod;
}

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

    int dp[n + 1][m + 1];

    for(int i = 0; i <= n; i ++){
        for(int j = 0; j <= m; j ++){
            if(!i || !j){
                dp[i][j] = 1;
                continue;
            }

            dp[i][j] = dp[i - 1][j];
            add(dp[i][j], 4ll * j * dp[i - 1][j - 1]);

            if(i >= 2) add(dp[i][j], 1ll * j * (i - 1) * dp[i - 2][j - 1]);
            if(j >= 2) add(dp[i][j], 1ll * j * (j - 1) / 2 * dp[i - 1][j - 2]);
        }
    }

    add(dp[n][m], Mod - 1);

    cout << dp[n][m];
}

signed main()
{
    cin.tie(0)->sync_with_stdio(0);

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

    // cout << 1; return 0;

    ll n = 1;

    // cin >> n;

    while(n) {
        solve();
        n --;
        // cout << "\n";
    }

    // cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
    return 0;
}

//                                   ++++                                           
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//    -@      @*#@         #####%:::-====+:::==---**%#@ *%%%%@@@@@@-:               
//    -=-*%  #          #***--%%::::::::+=-+#-----=**@*#     #+**#@#                
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//                       %@@@@@@@@@==@+%%%%@   ----**** *#                          
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//                    #+++++++++#==++-::::::     @**** *#                           
//                   =+++++++++++==+++:::::::   ####@ #%                            
//                  +++++++++++=@ @++++::::::@      @#                              
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//             ++++++-@               =+++:+::                                      
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//          +::=:::::                  @+*+:-+++-:                                  
//        @::+-:::::#                     +++::::::@                                
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//     @:+@*:::::::****@                   +@+++:-=*:*@                             
//    *:@@%::::::::=****                   @%@+++:::#**@                            
//   *%@@@-:::::::%=+==*@                   +@%+++:***+*                            
//  #%@@%%::::::::#+=-=#                    =+@+++++:::*+                           
// @####+::::::::%+=@#%#=@                  @**@@%=++::::@                          
// @   +:::::::::***#*@ @@###+=+=%@          +**#+=+*+:::-                          
//    =-:::::::%%%%@@          @#=*########%#+*%%+--@*+::%                          
//   +---%@                                   @@ =-:-**:#                           
//  %%%%%                                        @+--*@                             
// @%%%%@                                        @%%%%%                             
//                                                @%%@@

Compilation message (stderr)

tents.cpp: In function 'int main()':
tents.cpp:59:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |         freopen("placeholder.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tents.cpp:60:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   60 |         freopen("placeholder.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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