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Submission #527620

# Submission time Handle Problem Language Result Execution time Memory
527620 2022-02-17T19:26:15 Z FireGhost1301 Kangaroo (CEOI16_kangaroo) C++11
100 / 100
 36 ms 14084 KB 
#include <bits/stdc++.h>
using namespace std;

const int MOD = 1e9 + 7;
void add(int &x, int y) {
    x += y;
    while (x >= MOD) x -= MOD;
    while (x < 0) x += MOD;
}

int mul(int x, int y) {
    return (x * 1LL * y) % MOD;
}

const int N = 2e3 + 3;
int n, s, t;
int f[N][N];

void solve() {
    cin >> n >> s >> t;

    f[1][1] = 1;

    for (int i = 1; i < n; ++i) {
        for (int j = 1; j <= i; ++j) if (f[i][j]) {
            if (i + 1 == s || i + 1 == t) {
                add(f[i + 1][j], f[i][j]);
                add(f[i + 1][j + 1], f[i][j]);
            }
            else {
                int x = (i >= s) + (i >= t);
                add(f[i + 1][j + 1], mul(f[i][j], j - x + 1));
                add(f[i + 1][j - 1], mul(f[i][j], j - 1));
            }
        }
    }

    cout << f[n][1];
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    solve();
    return 0;
}

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 324 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 324 KB Output is correct
2 Correct 1 ms 332 KB Output is correct
3 Correct 1 ms 332 KB Output is correct
4 Correct 1 ms 460 KB Output is correct
5 Correct 1 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 444 KB Output is correct
9 Correct 1 ms 460 KB Output is correct
10 Correct 0 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 324 KB Output is correct
2 Correct 1 ms 332 KB Output is correct
3 Correct 1 ms 332 KB Output is correct
4 Correct 1 ms 460 KB Output is correct
5 Correct 1 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 444 KB Output is correct
9 Correct 1 ms 460 KB Output is correct
10 Correct 0 ms 460 KB Output is correct
11 Correct 1 ms 460 KB Output is correct
12 Correct 1 ms 1100 KB Output is correct
13 Correct 1 ms 1100 KB Output is correct
14 Correct 1 ms 1100 KB Output is correct
15 Correct 1 ms 1100 KB Output is correct
16 Correct 1 ms 1100 KB Output is correct
17 Correct 1 ms 1092 KB Output is correct
18 Correct 1 ms 1100 KB Output is correct
19 Correct 1 ms 1100 KB Output is correct
20 Correct 1 ms 1088 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 324 KB Output is correct
2 Correct 1 ms 332 KB Output is correct
3 Correct 1 ms 332 KB Output is correct
4 Correct 1 ms 460 KB Output is correct
5 Correct 1 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 444 KB Output is correct
9 Correct 1 ms 460 KB Output is correct
10 Correct 0 ms 460 KB Output is correct
11 Correct 1 ms 460 KB Output is correct
12 Correct 1 ms 1100 KB Output is correct
13 Correct 1 ms 1100 KB Output is correct
14 Correct 1 ms 1100 KB Output is correct
15 Correct 1 ms 1100 KB Output is correct
16 Correct 1 ms 1100 KB Output is correct
17 Correct 1 ms 1092 KB Output is correct
18 Correct 1 ms 1100 KB Output is correct
19 Correct 1 ms 1100 KB Output is correct
20 Correct 1 ms 1088 KB Output is correct
21 Correct 4 ms 3788 KB Output is correct
22 Correct 7 ms 4032 KB Output is correct
23 Correct 6 ms 4428 KB Output is correct
24 Correct 36 ms 14012 KB Output is correct
25 Correct 25 ms 14028 KB Output is correct
26 Correct 27 ms 14084 KB Output is correct
27 Correct 26 ms 14004 KB Output is correct
28 Correct 16 ms 10168 KB Output is correct