oj.uz

Submission #24760

# Submission time Handle Problem Language Result Execution time Memory
24760 2017-06-13T03:39:25 Z nibnalin Kangaroo (CEOI16_kangaroo) C++14
100 / 100
 163 ms 127680 KB 
#include <iostream>
#include <cstdio>
#include <vector>
using namespace std;

typedef long long int lli;

const lli maxn = lli(2e3)+5, MOD = lli(1e9)+7;

lli n, cs, cf, memo[maxn][maxn][2][2];

inline lli c2(lli x)
{
	return ((x*(x-1ll)))%MOD;
}

lli DP(lli idx, lli chains, lli start, lli end)
{
	if(idx == n) return (!start && !end && !chains);
	if(idx > cs && !start) return 0;
	if(idx > cf && !end) return 0;
	else if(memo[idx][chains][start][end] != -1) return memo[idx][chains][start][end]%MOD;
	else if(idx == cs)
	{
		lli res = DP(idx+1, chains, 1, end)%MOD;
		if(chains)
		{
			res += chains*DP(idx+1, chains-1, 1, end)%MOD;
			res %= MOD;
		}
		if(end)
		{
			res += DP(idx+1, chains, 0, 0)%MOD;
			res %= MOD;
		}
		res %= MOD;
		memo[idx][chains][start][end] = res;
		//cout << idx << " " << chains << " " << start << " " << end << ": " << res << "\n";
		return res;
	}
	else if(idx == cf)
	{
		lli res = DP(idx+1, chains, start, 1)%MOD;
		if(chains)
		{
			res += chains*DP(idx+1, chains-1, start, 1)%MOD;
			res %= MOD;
		}
		if(start)
		{
			res += DP(idx+1, chains, 0, 0)%MOD;
			res %= MOD;
		}
		res %= MOD;
		memo[idx][chains][start][end] = res;
		//cout << idx << " " << chains << " " << start << " " << end << ": " << res << "\n";
		return res;
	}
	else
	{
		lli res = DP(idx+1, chains+1, start, end)%MOD;
		if(chains > 1)
		{
			res += c2(chains)*DP(idx+1, chains-1, start, end)%MOD;
			res %= MOD;
		}
		if(start && chains)
		{
			res += chains*DP(idx+1, chains-1, start, end)%MOD;
			res %= MOD;
		}
		if(chains && end)
		{
			res += chains*DP(idx+1, chains-1, start, end)%MOD;
			res %= MOD;
		}
		if(start && end)
		{
			res += DP(idx+1, chains, start-1, end-1)%MOD;
			res %= MOD;
		}
		res %= MOD;
		memo[idx][chains][start][end] = res;
		//cout << idx << " " << chains << " " << start << " " << end << ": " << res << "\n";
		return res;
	}
}

int main(void)
{
	scanf("%lld%lld%lld", &n, &cs, &cf);
	cs--, cf--;

	for(lli i = 0;i <= n;i++)
	{
		for(lli j = 0;j <= n;j++)
		{
			for(lli k = 0;k < 2;k++)
			{
				for(lli l = 0;l < 2;l++) memo[i][j][k][l] = -1;
			}
		}
	
	}

	printf("%lld\n", DP(0, 0, 0, 0)%MOD);
}

Compilation message

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:91:37: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld%lld%lld", &n, &cs, &cf);
                                     ^

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 127644 KB Output is correct
2 Correct 0 ms 127644 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 127644 KB Output is correct
2 Correct 0 ms 127644 KB Output is correct
3 Correct 0 ms 127644 KB Output is correct
4 Correct 0 ms 127644 KB Output is correct
5 Correct 0 ms 127644 KB Output is correct
6 Correct 0 ms 127644 KB Output is correct
7 Correct 0 ms 127644 KB Output is correct
8 Correct 0 ms 127644 KB Output is correct
9 Correct 0 ms 127644 KB Output is correct
10 Correct 0 ms 127644 KB Output is correct
11 Correct 0 ms 127644 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 127644 KB Output is correct
2 Correct 0 ms 127644 KB Output is correct
3 Correct 0 ms 127644 KB Output is correct
4 Correct 0 ms 127644 KB Output is correct
5 Correct 0 ms 127644 KB Output is correct
6 Correct 0 ms 127644 KB Output is correct
7 Correct 0 ms 127644 KB Output is correct
8 Correct 0 ms 127644 KB Output is correct
9 Correct 0 ms 127644 KB Output is correct
10 Correct 0 ms 127644 KB Output is correct
11 Correct 0 ms 127644 KB Output is correct
12 Correct 0 ms 127644 KB Output is correct
13 Correct 0 ms 127644 KB Output is correct
14 Correct 0 ms 127644 KB Output is correct
15 Correct 0 ms 127644 KB Output is correct
16 Correct 0 ms 127644 KB Output is correct
17 Correct 0 ms 127644 KB Output is correct
18 Correct 0 ms 127644 KB Output is correct
19 Correct 0 ms 127644 KB Output is correct
20 Correct 0 ms 127644 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 127644 KB Output is correct
2 Correct 0 ms 127644 KB Output is correct
3 Correct 0 ms 127644 KB Output is correct
4 Correct 0 ms 127644 KB Output is correct
5 Correct 0 ms 127644 KB Output is correct
6 Correct 0 ms 127644 KB Output is correct
7 Correct 0 ms 127644 KB Output is correct
8 Correct 0 ms 127644 KB Output is correct
9 Correct 0 ms 127644 KB Output is correct
10 Correct 0 ms 127644 KB Output is correct
11 Correct 0 ms 127644 KB Output is correct
12 Correct 0 ms 127644 KB Output is correct
13 Correct 0 ms 127644 KB Output is correct
14 Correct 0 ms 127644 KB Output is correct
15 Correct 0 ms 127644 KB Output is correct
16 Correct 0 ms 127644 KB Output is correct
17 Correct 0 ms 127644 KB Output is correct
18 Correct 0 ms 127644 KB Output is correct
19 Correct 0 ms 127644 KB Output is correct
20 Correct 0 ms 127644 KB Output is correct
21 Correct 16 ms 127644 KB Output is correct
22 Correct 13 ms 127644 KB Output is correct
23 Correct 16 ms 127644 KB Output is correct
24 Correct 146 ms 127676 KB Output is correct
25 Correct 156 ms 127672 KB Output is correct
26 Correct 146 ms 127680 KB Output is correct
27 Correct 163 ms 127672 KB Output is correct
28 Correct 93 ms 127644 KB Output is correct