Submission #636152

#	Time	Username	Problem	Language	Result	Execution time	Memory
636152		Do_you_copy	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	24 ms	23016 KiB

kangaroo

#include <bits/stdc++.h>
#define int long long
#define fi first
#define se second
#define pb push_back
#define faster ios_base::sync_with_stdio(0); cin.tie(0);
using namespace std;
using ll = long long;
using ull = unsigned ll;
using ld = long double;
using pii = pair <int, int>;
using pil = pair <int, ll>;
using pli = pair <ll, int>;
using pll = pair <ll, ll>;
mt19937 Rand(chrono::steady_clock::now().time_since_epoch().count());

ll min(const ll &a, const ll &b){
    return (a < b) ? a : b;
}

ll max(const ll &a, const ll &b){
    return (a > b) ? a : b;
}

const ll Mod = 1000000007;
//const ll Mod2 = 999999999989;
//only use when required
const int maxN = 2e3 + 2;
int n;
int cf, cs;
int dp[maxN][maxN];
void Init(){
    cin >> n;
    cin >> cf >> cs;
    dp[0][0] = 1;
    for (int i = 1; i <= n; ++i){
        for (int j = 1; j <= i + 1; ++j){
            if (i == cs || i == cf){
                dp[i][j] = dp[i - 1][j] + dp[i - 1][j - 1];
                dp[i][j] %= Mod;
            }
            else{
                dp[i][j] += dp[i - 1][j + 1] * j;
                dp[i][j] += dp[i - 1][j - 1] * (j - (cs < i) - (cf < i));
                dp[i][j] %= Mod;
            }
        }
    }
    cout << dp[n][1];
}

#define debu
#define taskname "test"
signed main(){
    if (fopen(taskname".inp", "r")){
        freopen(taskname".inp", "r", stdin);
        #ifdef debug
        freopen(taskname".out", "w", stdout);
        #endif
    }
    faster;
    ll tt = 1;
    //cin >> tt;
    while (tt--){
        Init();
    }
    if (fopen("timeout.txt", "r")){
        ofstream timeout("timeout.txt");
        timeout << 1000 * double(clock()) / CLOCKS_PER_SEC;
        #ifndef debug
        cerr << "\nTime elapsed: " << 1000 * double(clock()) / CLOCKS_PER_SEC << "ms\n";
        #endif
    }
}

Compilation message (stderr)

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:56:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   56 |         freopen(taskname".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 30 / 30
• Subtask 3: 15 / 15
• Subtask 4: 49 / 49