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Submission #660529

# Submission time Handle Problem Language Result Execution time Memory
660529 2022-11-22T07:47:28 Z Alex_tz307 Kangaroo (CEOI16_kangaroo) C++17
100 / 100
 11 ms 328 KB 
#include <bits/stdc++.h>

using namespace std;

const int kN = 2e3;
const int mod = 1e9 + 7;
int dp[2][1 + kN];

void addSelf(int &x, int y) {
  x += y;
  if (x >= mod) {
    x -= mod;
  }
}

int add(int x, int y) {
  addSelf(x, y);
  return x;
}

void multSelf(int &x, int y) {
  x = (int64_t)x * y % mod;
}

int mult(int x, int y) {
  multSelf(x, y);
  return x;
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int n, first, last;
  cin >> n >> first >> last;
  dp[1][1] = 1;
  for (int i = 2, t = 0; i <= n; ++i, t ^= 1) {
    for (int j = 1; j <= i; ++j) {
      if (i == first || i == last) {
        dp[t][j] = add(dp[t ^ 1][j - 1], dp[t ^ 1][j]);
      } else {
        dp[t][j] = add(mult(dp[t ^ 1][j + 1], j), mult(dp[t ^ 1][j - 1], j - (i > first) - (i > last)));
      }
    }
  }
  cout << dp[n & 1][1] << '\n';
  return 0;
}

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 1 ms 212 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 1 ms 212 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 1 ms 324 KB Output is correct
14 Correct 1 ms 320 KB Output is correct
15 Correct 1 ms 212 KB Output is correct
16 Correct 1 ms 212 KB Output is correct
17 Correct 1 ms 212 KB Output is correct
18 Correct 1 ms 212 KB Output is correct
19 Correct 1 ms 212 KB Output is correct
20 Correct 1 ms 212 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 1 ms 212 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 1 ms 324 KB Output is correct
14 Correct 1 ms 320 KB Output is correct
15 Correct 1 ms 212 KB Output is correct
16 Correct 1 ms 212 KB Output is correct
17 Correct 1 ms 212 KB Output is correct
18 Correct 1 ms 212 KB Output is correct
19 Correct 1 ms 212 KB Output is correct
20 Correct 1 ms 212 KB Output is correct
21 Correct 2 ms 212 KB Output is correct
22 Correct 2 ms 212 KB Output is correct
23 Correct 2 ms 212 KB Output is correct
24 Correct 10 ms 212 KB Output is correct
25 Correct 9 ms 328 KB Output is correct
26 Correct 11 ms 324 KB Output is correct
27 Correct 10 ms 328 KB Output is correct
28 Correct 8 ms 328 KB Output is correct