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Submission #684901

# Submission time Handle Problem Language Result Execution time Memory
684901 2023-01-22T19:18:01 Z ToniB Kangaroo (CEOI16_kangaroo) C++17
100 / 100
 13 ms 14092 KB 
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2005;
const int MOD = 1e9 + 7;

int add(int a, int b){ return (a + b >= MOD) ? a + b - MOD : a + b; }
int sub(int a, int b){ return (a - b < 0) ? a - b + MOD : a - b; }
int mul(int a, int b){ return (long long) a * b % MOD; }

int n, s, f, dp[MAXN][MAXN];

int main(){
	cin >> n >> s >> f;
	if(s > f) swap(s, f);
	dp[0][0] = 1;
	for(int i = 1; i <= n; ++i){
		for(int j = 1; j <= i; ++j){
//			if(max(s, f) <= i && i < n && j == 1) continue;
			int choose = mul(j, j + 1);
			if(s < i && i < f) choose = sub(choose, j);
			else if(f < i) choose = sub(choose, 2 * j);
			else if(i == s) choose = j;
			else if(i == f) choose = j - 1;
			if(i == n) choose = 1;

			if(i == s || i == f){
				dp[i][j] = add(dp[i - 1][j - 1], mul(dp[i - 1][j], choose));
			} else {
				dp[i][j] = add(dp[i - 1][j - 1], mul(dp[i - 1][j + 1], choose));
			}
		}
	}
	cout << dp[n][1];
	return 0;
}

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 340 KB Output is correct
4 Correct 0 ms 468 KB Output is correct
5 Correct 1 ms 468 KB Output is correct
6 Correct 0 ms 468 KB Output is correct
7 Correct 0 ms 340 KB Output is correct
8 Correct 0 ms 468 KB Output is correct
9 Correct 0 ms 468 KB Output is correct
10 Correct 0 ms 468 KB Output is correct
11 Correct 0 ms 468 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 340 KB Output is correct
4 Correct 0 ms 468 KB Output is correct
5 Correct 1 ms 468 KB Output is correct
6 Correct 0 ms 468 KB Output is correct
7 Correct 0 ms 340 KB Output is correct
8 Correct 0 ms 468 KB Output is correct
9 Correct 0 ms 468 KB Output is correct
10 Correct 0 ms 468 KB Output is correct
11 Correct 0 ms 468 KB Output is correct
12 Correct 1 ms 1108 KB Output is correct
13 Correct 1 ms 1108 KB Output is correct
14 Correct 1 ms 1108 KB Output is correct
15 Correct 1 ms 1108 KB Output is correct
16 Correct 1 ms 1108 KB Output is correct
17 Correct 1 ms 1108 KB Output is correct
18 Correct 1 ms 980 KB Output is correct
19 Correct 1 ms 1108 KB Output is correct
20 Correct 1 ms 1108 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 340 KB Output is correct
4 Correct 0 ms 468 KB Output is correct
5 Correct 1 ms 468 KB Output is correct
6 Correct 0 ms 468 KB Output is correct
7 Correct 0 ms 340 KB Output is correct
8 Correct 0 ms 468 KB Output is correct
9 Correct 0 ms 468 KB Output is correct
10 Correct 0 ms 468 KB Output is correct
11 Correct 0 ms 468 KB Output is correct
12 Correct 1 ms 1108 KB Output is correct
13 Correct 1 ms 1108 KB Output is correct
14 Correct 1 ms 1108 KB Output is correct
15 Correct 1 ms 1108 KB Output is correct
16 Correct 1 ms 1108 KB Output is correct
17 Correct 1 ms 1108 KB Output is correct
18 Correct 1 ms 980 KB Output is correct
19 Correct 1 ms 1108 KB Output is correct
20 Correct 1 ms 1108 KB Output is correct
21 Correct 2 ms 3668 KB Output is correct
22 Correct 3 ms 3988 KB Output is correct
23 Correct 4 ms 4436 KB Output is correct
24 Correct 12 ms 14048 KB Output is correct
25 Correct 13 ms 14036 KB Output is correct
26 Correct 13 ms 14092 KB Output is correct
27 Correct 12 ms 14036 KB Output is correct
28 Correct 8 ms 10068 KB Output is correct