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Submission #308921

# Submission time Handle Problem Language Result Execution time Memory
308921 2020-10-02T09:47:35 Z arnold518 Kangaroo (CEOI16_kangaroo) C++14
100 / 100
 71 ms 32120 KB 
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 2000;
const ll MOD = 1e9+7;

int N, S, E;

ll dp[MAXN+10][MAXN+10];

ll solve(int pos, int comp)
{
	if(pos==N+1)
	{
		if(comp==1) return 1;
		else return 0;
	}
	ll &ret=dp[pos][comp];
	if(ret!=-1) return ret;

	ret=0;

	if(pos==S)
	{
		ret+=solve(pos+1, comp);
		ret+=solve(pos+1, comp+1);
	}
	else if(pos==E)
	{
		ret+=solve(pos+1, comp);
		ret+=solve(pos+1, comp+1);
	}
	else if(pos<S)
	{
		if(comp>=2) ret+=(comp-1)*solve(pos+1, comp-1);
		ret+=(comp+1)*solve(pos+1, comp+1);
	}
	else if(pos<E)
	{
		if(comp>=2) ret+=(comp-1)*solve(pos+1, comp-1);
		ret+=(comp)*solve(pos+1, comp+1);	
	}
	else
	{
		if(comp>=2) ret+=(comp-1)*solve(pos+1, comp-1);
		ret+=(comp-1)*solve(pos+1, comp+1);		
	}
	ret%=MOD;
	//printf("%d %d : %lld\n", pos, comp, ret);
	return ret;
}

int main()
{
	scanf("%d%d%d", &N, &S, &E); if(S>E) swap(S, E);
	memset(dp, -1, sizeof(dp));
	printf("%lld\n", solve(1, 0));

}

Compilation message

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:59:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   59 |  scanf("%d%d%d", &N, &S, &E); if(S>E) swap(S, E);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 19 ms 31872 KB Output is correct
2 Correct 19 ms 32000 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 19 ms 31872 KB Output is correct
2 Correct 19 ms 32000 KB Output is correct
3 Correct 19 ms 31872 KB Output is correct
4 Correct 21 ms 32000 KB Output is correct
5 Correct 20 ms 32000 KB Output is correct
6 Correct 23 ms 31872 KB Output is correct
7 Correct 19 ms 31872 KB Output is correct
8 Correct 20 ms 31872 KB Output is correct
9 Correct 19 ms 31872 KB Output is correct
10 Correct 19 ms 31872 KB Output is correct
11 Correct 20 ms 32000 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 19 ms 31872 KB Output is correct
2 Correct 19 ms 32000 KB Output is correct
3 Correct 19 ms 31872 KB Output is correct
4 Correct 21 ms 32000 KB Output is correct
5 Correct 20 ms 32000 KB Output is correct
6 Correct 23 ms 31872 KB Output is correct
7 Correct 19 ms 31872 KB Output is correct
8 Correct 20 ms 31872 KB Output is correct
9 Correct 19 ms 31872 KB Output is correct
10 Correct 19 ms 31872 KB Output is correct
11 Correct 20 ms 32000 KB Output is correct
12 Correct 20 ms 31872 KB Output is correct
13 Correct 19 ms 31920 KB Output is correct
14 Correct 21 ms 32000 KB Output is correct
15 Correct 20 ms 31992 KB Output is correct
16 Correct 20 ms 32000 KB Output is correct
17 Correct 19 ms 32000 KB Output is correct
18 Correct 19 ms 32000 KB Output is correct
19 Correct 19 ms 32000 KB Output is correct
20 Correct 19 ms 32000 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 19 ms 31872 KB Output is correct
2 Correct 19 ms 32000 KB Output is correct
3 Correct 19 ms 31872 KB Output is correct
4 Correct 21 ms 32000 KB Output is correct
5 Correct 20 ms 32000 KB Output is correct
6 Correct 23 ms 31872 KB Output is correct
7 Correct 19 ms 31872 KB Output is correct
8 Correct 20 ms 31872 KB Output is correct
9 Correct 19 ms 31872 KB Output is correct
10 Correct 19 ms 31872 KB Output is correct
11 Correct 20 ms 32000 KB Output is correct
12 Correct 20 ms 31872 KB Output is correct
13 Correct 19 ms 31920 KB Output is correct
14 Correct 21 ms 32000 KB Output is correct
15 Correct 20 ms 31992 KB Output is correct
16 Correct 20 ms 32000 KB Output is correct
17 Correct 19 ms 32000 KB Output is correct
18 Correct 19 ms 32000 KB Output is correct
19 Correct 19 ms 32000 KB Output is correct
20 Correct 19 ms 32000 KB Output is correct
21 Correct 23 ms 32032 KB Output is correct
22 Correct 23 ms 32000 KB Output is correct
23 Correct 24 ms 32036 KB Output is correct
24 Correct 70 ms 32000 KB Output is correct
25 Correct 62 ms 32000 KB Output is correct
26 Correct 66 ms 32000 KB Output is correct
27 Correct 71 ms 32120 KB Output is correct
28 Correct 44 ms 32000 KB Output is correct