oj.uz

Submission #249728

# Submission time Handle Problem Language Result Execution time Memory
249728 2020-07-15T15:51:11 Z mraron Kangaroo (CEOI16_kangaroo) C++14
6 / 100
 1 ms 512 KB 
#include<iostream>
#include<vector>
#include<map>
#include<set>
#include<cassert>
#include<cassert>
#include<unordered_map>
#include<unordered_set>
#include<functional>
#include<queue>
#include<stack>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<sstream>
#include<iomanip>
#include<cstdio>
#include<cstdlib>
#include<numeric>
#include<random>
#include<chrono>
#include<bitset>
using namespace std;

#define all(x) (x).begin(), (x).end()
#define pb push_back
#define xx first
#define yy second
#define sz(x) (int)(x).size()
#define gc getchar
#define IO ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define mp make_pair

#ifndef ONLINE_JUDGE
#  define LOG(x) (cerr << #x << " = " << (x) << endl)
#else
#  define LOG(x) ((void)0)
#endif

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;

const double PI=acos(-1);
const ll INF = 1LL<<62;
const ll MINF = -(1LL<<62);

template<typename T> T getint() {
	T val=0;
	char c;
	
	bool neg=false;
	while((c=gc()) && !(c>='0' && c<='9')) {
		neg|=c=='-';
	}

	do {
		val=(val*10)+c-'0';
	} while((c=gc()) && (c>='0' && c<='9'));

	return val*(neg?-1:1);
}

//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count()); uniform_int_distribution<int>(0, n-1)(rng)


const ll mod=1e9+7;

ll dp[2001][2001];

int main() {
	IO;
	ll n,st,en;
	cin>>n>>st>>en;
	dp[1][1]=1;
	for(ll i=2;i<=n;++i) {
		for(ll j=1;j<=i;++j) {
			int cnt=(i>=st)+(i>=en);
			if(i==st) {
				//~ LOG(j);
				//~ LOG(j-cnt+1);
				dp[i][j]=(dp[i][j]+dp[i-1][j]*(j-cnt+1+(i==n)))%mod;
				dp[i][j]=(dp[i][j]+dp[i-1][j-1])%mod;
			}else if(i==en) {
				dp[i][j]=(dp[i][j]+dp[i-1][j]*(j-cnt+1+(i==n)))%mod;
				dp[i][j]=(dp[i][j]+dp[i-1][j-1])%mod;
			}else {
				dp[i][j]=(dp[i][j]+dp[i-1][j+1]*((j+1)*j-(i>=st)*j-(i>=en)*j+1*(i>=st&&i>=en)))%mod;
				dp[i][j]=(dp[i][j]+dp[i-1][j-1])%mod;
			}
		}
	}
	//~ LOG(dp[1][1]);
	//~ LOG(dp[2][2]);
	//~ LOG(dp[3][1]);
	//~ LOG(dp[3][2]);
	//~ LOG(dp[3][3]);
	//~ LOG(dp[4][1]);
	//~ LOG(dp[4][2]);
	//~ LOG(dp[4][3]);
	//~ LOG(dp[4][4]);
	cout<<dp[n][1]<<"\n";
	
	return 0;
}

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 384 KB Output is correct
2 Correct 0 ms 384 KB Output is correct

Subtask #2
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 384 KB Output is correct
2 Correct 0 ms 384 KB Output is correct
3 Correct 0 ms 384 KB Output is correct
4 Incorrect 0 ms 512 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #3
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 384 KB Output is correct
2 Correct 0 ms 384 KB Output is correct
3 Correct 0 ms 384 KB Output is correct
4 Incorrect 0 ms 512 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #4
0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 384 KB Output is correct
2 Correct 0 ms 384 KB Output is correct
3 Correct 0 ms 384 KB Output is correct
4 Incorrect 0 ms 512 KB Output isn't correct
5 Halted 0 ms 0 KB -