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Submission #376176

# Submission time Handle Problem Language Result Execution time Memory
376176 2021-03-11T03:22:13 Z YJU Kangaroo (CEOI16_kangaroo) C++14
100 / 100
 17 ms 23020 KB 
#include<bits/stdc++.h>
#pragma GCC optimize("unroll-loops,no-stack-protector,Ofast")
using namespace std;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef long double ld;
const ll N=2e3+5;
const ll MOD=1e9+7;
const ll INF=(1LL<<61);
const ld pi=acos(-1);
#define REP(i,n) for(int i=0;i<n;++i)
#define REP1(i,n) for(int i=1;i<=n;++i)
#define pb push_back
#define mp make_pair
#define X first
#define Y second
#define lwb lower_bound
#define SZ(_a) (ll)_a.size()

ll n,s,t,dp[N][N];

int main(){
	ios_base::sync_with_stdio(0);cin.tie(0);
	cin>>n>>s>>t;
	dp[1][1]=1;
	for(int i=2;i<=n;i++){
        for(int j=1;j<=i;j++){
			if(i==s||i==t){
                dp[i][j]=dp[i-1][j-1]+dp[i-1][j];
			}else{
				dp[i][j]=(dp[i-1][j+1]*j+dp[i-1][j-1]*(j-(i>s)-(i>t)))%MOD;
			}
			if(dp[i][j]>=MOD)dp[i][j]-=MOD;
		}
	}
	cout<<dp[n][1]<<"\n";
	return 0;
}
/*
*/

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 KB Output is correct
2 Correct 1 ms 364 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 492 KB Output is correct
4 Correct 1 ms 492 KB Output is correct
5 Correct 1 ms 492 KB Output is correct
6 Correct 1 ms 492 KB Output is correct
7 Correct 1 ms 492 KB Output is correct
8 Correct 1 ms 492 KB Output is correct
9 Correct 1 ms 492 KB Output is correct
10 Correct 1 ms 492 KB Output is correct
11 Correct 1 ms 492 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 492 KB Output is correct
4 Correct 1 ms 492 KB Output is correct
5 Correct 1 ms 492 KB Output is correct
6 Correct 1 ms 492 KB Output is correct
7 Correct 1 ms 492 KB Output is correct
8 Correct 1 ms 492 KB Output is correct
9 Correct 1 ms 492 KB Output is correct
10 Correct 1 ms 492 KB Output is correct
11 Correct 1 ms 492 KB Output is correct
12 Correct 1 ms 1260 KB Output is correct
13 Correct 1 ms 1260 KB Output is correct
14 Correct 1 ms 1260 KB Output is correct
15 Correct 1 ms 1260 KB Output is correct
16 Correct 1 ms 1260 KB Output is correct
17 Correct 1 ms 1260 KB Output is correct
18 Correct 1 ms 1132 KB Output is correct
19 Correct 1 ms 1296 KB Output is correct
20 Correct 1 ms 1260 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 492 KB Output is correct
4 Correct 1 ms 492 KB Output is correct
5 Correct 1 ms 492 KB Output is correct
6 Correct 1 ms 492 KB Output is correct
7 Correct 1 ms 492 KB Output is correct
8 Correct 1 ms 492 KB Output is correct
9 Correct 1 ms 492 KB Output is correct
10 Correct 1 ms 492 KB Output is correct
11 Correct 1 ms 492 KB Output is correct
12 Correct 1 ms 1260 KB Output is correct
13 Correct 1 ms 1260 KB Output is correct
14 Correct 1 ms 1260 KB Output is correct
15 Correct 1 ms 1260 KB Output is correct
16 Correct 1 ms 1260 KB Output is correct
17 Correct 1 ms 1260 KB Output is correct
18 Correct 1 ms 1132 KB Output is correct
19 Correct 1 ms 1296 KB Output is correct
20 Correct 1 ms 1260 KB Output is correct
21 Correct 3 ms 4716 KB Output is correct
22 Correct 3 ms 5100 KB Output is correct
23 Correct 4 ms 5612 KB Output is correct
24 Correct 17 ms 23020 KB Output is correct
25 Correct 17 ms 23020 KB Output is correct
26 Correct 16 ms 23020 KB Output is correct
27 Correct 16 ms 22892 KB Output is correct
28 Correct 10 ms 15084 KB Output is correct