제출 #632921

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
632921		Cyber_Wolf	캥거루 (CEOI16_kangaroo)	C++14	0 / 100	1 ms	724 KiB

kangaroo

// Problem: P2 - Kangaroo
// Contest: DMOJ - CEOI '16
// URL: https://dmoj.ca/problem/ceoi16p2
// Memory Limit: 512 MB
// Time Limit: 1000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#pragma GCC optimize("Ofast")

using namespace std;
using namespace __gnu_pbds;

#define lg long long
#define ordered_set	tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define fastio ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define error(args...) { string _s = #args; replace(_s.begin(), _s.end(), ',', ' '); stringstream _ss(_s); istream_iterator<string> _it(_ss); err(_it, args);
#define endl \n
#define lbound(x, y) lower_bound(x.begin(), x.end(), y) 
#define ubound(x, y) upper_bound(x.begin(), x.end(), y) 
#define sortasc(v) sort(v.begin(), v.end())	
#define sortdesc(v) sort(v.rbegin(), v.rend())	
#define custom_array(a,l, r) int _##a[r-l+1]; int*a=_##a-l;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const lg MOD = 1e9+7, N = 4e2+5, M = 1e7+1, SZ = 1e3+1;
/*
bitset<N> primes;
lg pwrs[N], inv[N];

lg fast_power(lg n, lg k)
{
	if(!k)	return 1;
	if(k&1)	return (fast_power(n, k-1)*n)%MOD;
	lg x = fast_power(n, k/2)%MOD;
	return (x*x)%MOD;
}

void sieve()
{
	primes.set();
	primes[0] = primes[1] = 0;
	for(lg i = 2; i < N; i++)
	{
		if(!primes[i])	continue;
		for(lg j = i*i; j < N; j += i)
		{
			primes[j] = 0;
		}
	}
	return;
}

struct matrix
{
	vector<vector<lg>> con = vector<vector<lg>> (SZ, vector<lg> (SZ));
	matrix operator *(const matrix& a)
	{
		matrix product;
		for(int i = 0; i < (lg)con.size(); i++)
		{
			for(int j = 0; j < (lg)a.con[0].size(); j++)
			{
				for(int k = 0; k < (lg)a.con.size(); k++)
				{
					product.con[i][j] = (product.con[i][j]+(con[i][k]*a.con[k][j])%MOD)%MOD; 
				}
			}
		}
		return product;
	}
};

void preprocess(lg x)
{
	inv[2e5] = fast_power(x, MOD-2);
	for(int i = 2e5-1; i > 1; i--)
	{
		inv[i] = (inv[i+1]*i)%MOD;
	}
	pwrs[0] = 1;
	for(int i = 1; i <= 2e5; i++)
	{
		pwrs[i] = (pwrs[i]*i)%MOD;
	}
	return;
}

*/
lg n, st, en;

lg dp[2][N][N][N];

lg solve(lg dir, lg a, lg b, lg c)
{
	if(~dp[dir][a][b][c])	return dp[dir][a][b][c];
	auto &ret = dp[dir][a][b][c];
	ret = 0;
	if(!dir)
	{
		for(int idx = 0; idx < b; idx++)
		{
			ret = (solve(1, c, b-1-idx, a+idx)+ret)%MOD;
		}
		for(int idx = 0; idx < c; idx++)
		{
			ret = (solve(0, c-1-idx, b+idx, a)+ret)%MOD;
		}
	}
	else{
		for(int idx = 0; idx < c; idx++)
		{
			ret = (solve(0, c-1-idx, b+idx, a)+ret)%MOD;
		}
	}
	return ret;
}

int main()
{
	fastio;
	cin >> n >> st >> en;
	if(st > en)	swap(st, en);
	for(int i = 0; i < 2; i++)
	{
		for(int j = 0; j <= n; j++)
		{
			for(int k = 0; k <= n; k++)
			{
				memset(dp[i][j][k], -1, sizeof(dp[i][j][k]));
			}
		}
	}
	dp[0][0][0][0] = dp[1][0][0][0] = 1;
	cout << (solve(0, st-1, en-st-1, n-en)+solve(1, n-en, en-st-1, st-1))%MOD << '\n';

    return 0;
}

• Subtask 1: 0 / 6
• Subtask 2: 0 / 30
• Subtask 3: 0 / 15
• Subtask 4: 0 / 49