Submission #741249

#	Time	Username	Problem	Language	Result	Execution time	Memory
741249		sunwukong123	Kangaroo (CEOI16_kangaroo)	C++14	0 / 100	1 ms	340 KiB

kangaroo

#include <bits/stdc++.h>
using namespace std;
#define int long long 
#define FOR(i,s,e) for(int i = s; i <= (int)e; ++i)
#define DEC(i,s,e) for(int i = s; i >= (int)e; --i)
#define IAMSPEED ios_base::sync_with_stdio(false); cin.tie(0);
#ifdef LOCAL
#define db(x) cerr << #x << "=" << x << "\n"
#define db2(x, y) cerr << #x << "=" << x << " , " << #y << "=" << y << "\n"
#define db3(a,b,c) cerr<<#a<<"="<<a<<","<<#b<<"="<<b<<","<<#c<<"="<<c<<"\n"
#define dbv(v) cerr << #v << ":"; for (auto ite : v) cerr << ite << ' '; cerr <<"\n"
#define dbvp(v) cerr << #v << ":"; for (auto ite : v) cerr << "{"  << ite.f << ',' << ite.s << "} "; cerr << "\n"
#define dba(a,ss,ee) cerr << #a << ":"; FOR(ite,ss,ee) cerr << a[ite] << ' '; cerr << "\n"
#define reach cerr << "LINE: " << __LINE__ << "\n";
#else
#define reach 
#define db(x)
#define db2(x,y)
#define db3(a,b,c)
#define dbv(v)
#define dbvp(v)
#define dba(a,ss,ee)
#endif
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define f first 
#define s second
#define g0(x) get<0>(x)
#define g1(x) get<1>(x)
#define g2(x) get<2>(x)
#define g3(x) get<3>(x)
typedef pair <int, int> pi;
typedef tuple<int,int,int> ti3;
typedef tuple<int,int,int,int> ti4;
int rand(int a, int b) { return a + rng() % (b-a+1); }
const int MOD = 1e9 + 7;
const int inf = (int)1e9 + 500;
const long long oo = (long long)1e18 + 500;
template <typename T> void chmax(T& a, const T b) { a=max(a,b); }
template <typename T> void chmin(T& a, const T b) { a=min(a,b); }
const int MAXN = 2005;
int n,a,b;
int dp[MAXN][MAXN];
int32_t main() 
{
	IAMSPEED
	cin >> n >> a >> b;
	dp[0][0+1]=1;
	FOR(i,0,n-1){
		FOR(j,-1,n){
			if(dp[i][j+1]){
				if(i+1==a){
					dp[i+1][j+1]=(dp[i+1][j+1]+dp[i][j+1])%MOD;
					dp[i+1][j-1+1]=(dp[i+1][j-1+1]+dp[i][j+1])%MOD;
				} else if(i+1==b){
					dp[i+1][j+1]=(dp[i+1][j+1]+dp[i][j+1])%MOD;
					dp[i+1][j-1+1]=(dp[i+1][j-1+1]+dp[i][j+1])%MOD;
				} else{
					dp[i+1][j+1+1]=dp[i][j+1]*(j+1)%MOD;
					dp[i+1][j-1+1]=dp[i][j+1]*(j+(i>=a) && (i>=b))%MOD;
				}
			}
			
		}
	}
	cout<<dp[n][0];
}

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