Submission #797816

#	Time	Username	Problem	Language	Result	Execution time	Memory
797816		amirhoseinfar1385	Kangaroo (CEOI16_kangaroo)	C++17	0 / 100	1 ms	340 KiB

kangaroo

#include<bits/stdc++.h>
using namespace std;
const int maxn=200+10;
int mod=1e9+7;
long long dp[maxn][maxn][maxn][2],pd[maxn][maxn];
int n,s,e;

int ww(long  long a){
	a%=mod;
	return a;
}

void calpd(){
	pd[1][1]=1;
	for(int i=2;i<=n;i++){
		if((i&1)==0){
			for(int j=1;j<=i;j++){
				pd[i][j]=pd[i][j-1]+pd[i-1][i-j+1];
				pd[i][j]=ww(pd[i][j]);
			}
		}
		else{
			for(int j=2;j<=i;j++){
				pd[i][j]=pd[i][j-1]+mod-pd[i-1][j-1]+pd[i-1][i-j+1];
				pd[i][j]=ww(pd[i][j]);
			}
		}
	}
}

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>s>>e;
	if(s>e){
		swap(s,e);
	}
	calpd();
	dp[0][0][0][0]=1;
	for(int sum=1;sum<=n;sum++){
		for(int fn=1;fn<=sum;fn++){
			for(int i=sum-fn;i>=0;i--){
				int j=sum-fn-i;
				for(int k=0;k<2;k++){
					dp[fn][i][j][k]=dp[fn-1][i+1][j][k];
					if(k==0){
						dp[fn][i][j][k]+=pd[j+i+fn][j+1];
						dp[fn][i][j][k]+=dp[fn-1][i][j][k^1];
					}
					else{
						dp[fn][i][j][k]+=pd[fn+i+j][fn+i];
						dp[fn][i][j][k]+=mod-dp[fn-1][i][j][k^1];
					}
					dp[fn][i][j][k]=ww(ww(dp[fn][i][j][k]));
				}
			}
		}
	}
	int res=ww(dp[e-s][s-1][n-e][0]+dp[e-s][s-1][n-e][1]);
	s++;
	res+=mod-ww(dp[e-s][s-1][n-e][0]+dp[e-s][s-1][n-e][1]);
	res=ww(res);
	cout<<res<<"\n";
	return 0;
}

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