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Submission #461340

# Submission time Handle Problem Language Result Execution time Memory
461340 2021-08-09T21:52:31 Z izhang05 Kangaroo (CEOI16_kangaroo) C++17
100 / 100
 24 ms 22916 KB 
#include <bits/stdc++.h>

using namespace std;

//#define DEBUG
void setIO(const string &name) {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cin.exceptions(istream::failbit);
#ifdef LOCAL
    freopen((name + ".in").c_str(), "r", stdin);
    freopen((name + ".out").c_str(), "w", stdout);
    freopen((name + ".out").c_str(), "w", stderr);
#endif
}

const int inf = 0x3f3f3f3f, mod = 1e9 + 7, maxn = 2005;
const long long INFL = 0x3f3f3f3f3f3f3f3f;

long long dp[maxn][maxn];


int main() {
    setIO("1");

    int n, start, end;
    cin >> n >> start >> end;
    dp[1][1] = 1;
    for (int i = 2; i <= n; ++i) {
        for (int j = 1; j <= i; ++j) {
            long long &cur = dp[i][j];
            if (i == start || i == end) {
                cur = (dp[i - 1][j] + dp[i - 1][j - 1]) % mod;
            } else {
                cur += j * dp[i - 1][j + 1];
                cur %= mod;
                cur += (j - (i > start) - (i > end)) * dp[i - 1][j - 1];
                cur %= mod;
            }
        }
    }
    cout << dp[n][1] << "\n";
    return 0;
}

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 332 KB Output is correct
2 Correct 1 ms 332 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 332 KB Output is correct
2 Correct 1 ms 332 KB Output is correct
3 Correct 0 ms 332 KB Output is correct
4 Correct 1 ms 460 KB Output is correct
5 Correct 0 ms 460 KB Output is correct
6 Correct 1 ms 460 KB Output is correct
7 Correct 1 ms 460 KB Output is correct
8 Correct 1 ms 460 KB Output is correct
9 Correct 1 ms 460 KB Output is correct
10 Correct 1 ms 460 KB Output is correct
11 Correct 1 ms 460 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 332 KB Output is correct
2 Correct 1 ms 332 KB Output is correct
3 Correct 0 ms 332 KB Output is correct
4 Correct 1 ms 460 KB Output is correct
5 Correct 0 ms 460 KB Output is correct
6 Correct 1 ms 460 KB Output is correct
7 Correct 1 ms 460 KB Output is correct
8 Correct 1 ms 460 KB Output is correct
9 Correct 1 ms 460 KB Output is correct
10 Correct 1 ms 460 KB Output is correct
11 Correct 1 ms 460 KB Output is correct
12 Correct 1 ms 1228 KB Output is correct
13 Correct 1 ms 1100 KB Output is correct
14 Correct 1 ms 1240 KB Output is correct
15 Correct 1 ms 1228 KB Output is correct
16 Correct 1 ms 1228 KB Output is correct
17 Correct 1 ms 1228 KB Output is correct
18 Correct 1 ms 1100 KB Output is correct
19 Correct 1 ms 1228 KB Output is correct
20 Correct 2 ms 1228 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 332 KB Output is correct
2 Correct 1 ms 332 KB Output is correct
3 Correct 0 ms 332 KB Output is correct
4 Correct 1 ms 460 KB Output is correct
5 Correct 0 ms 460 KB Output is correct
6 Correct 1 ms 460 KB Output is correct
7 Correct 1 ms 460 KB Output is correct
8 Correct 1 ms 460 KB Output is correct
9 Correct 1 ms 460 KB Output is correct
10 Correct 1 ms 460 KB Output is correct
11 Correct 1 ms 460 KB Output is correct
12 Correct 1 ms 1228 KB Output is correct
13 Correct 1 ms 1100 KB Output is correct
14 Correct 1 ms 1240 KB Output is correct
15 Correct 1 ms 1228 KB Output is correct
16 Correct 1 ms 1228 KB Output is correct
17 Correct 1 ms 1228 KB Output is correct
18 Correct 1 ms 1100 KB Output is correct
19 Correct 1 ms 1228 KB Output is correct
20 Correct 2 ms 1228 KB Output is correct
21 Correct 4 ms 4556 KB Output is correct
22 Correct 5 ms 4940 KB Output is correct
23 Correct 5 ms 5580 KB Output is correct
24 Correct 23 ms 22904 KB Output is correct
25 Correct 24 ms 22908 KB Output is correct
26 Correct 23 ms 22916 KB Output is correct
27 Correct 23 ms 22740 KB Output is correct
28 Correct 17 ms 15044 KB Output is correct