Submission #1267321

#	Time	Username	Problem	Language	Result	Execution time	Memory
1267321		baotoan655	Kangaroo (CEOI16_kangaroo)	C++20	100 / 100	14 ms	14152 KiB

kangaroo

#include <bits/stdc++.h>
#define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
using namespace std;

const int MOD = 1e9 + 7;
inline int add(int x, int y) {
    x += y;
    if(x >= MOD) x -= MOD;
    return x;
}
inline int mul(int x, int y) {
    return (long long) x * y % MOD;
}
const int N = 2005;
int n, a, b;
int dp[N][N];

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

    file("A") else file("task");

    cin >> n >> a >> b;
    dp[1][1] = 1;
    for(int i = 2; i <= n; ++i) {
        for(int j = 1; j <= i; ++j) {
            if(i == a || i == b) {
                dp[i][j] = add(dp[i - 1][j], dp[i - 1][j - 1]);
            } else {
                if(j - (i > a) - (i > b) >= 0) dp[i][j] = add(dp[i][j], mul(dp[i - 1][j - 1], j - (i > a) - (i > b)));

                dp[i][j] = add(dp[i][j], mul(dp[i - 1][j + 1], j));
            }
        }
    }
    cout << dp[n][1] << '\n';
}

Compilation message (stderr)

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:2:58: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    2 | #define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
kangaroo.cpp:22:5: note: in expansion of macro 'file'
   22 |     file("A") else file("task");
      |     ^~~~
kangaroo.cpp:2:91: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    2 | #define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                                                    ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
kangaroo.cpp:22:5: note: in expansion of macro 'file'
   22 |     file("A") else file("task");
      |     ^~~~
kangaroo.cpp:2:58: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    2 | #define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
kangaroo.cpp:22:20: note: in expansion of macro 'file'
   22 |     file("A") else file("task");
      |                    ^~~~
kangaroo.cpp:2:91: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    2 | #define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                                                    ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
kangaroo.cpp:22:20: note: in expansion of macro 'file'
   22 |     file("A") else file("task");
      |                    ^~~~

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