Submission #797789

#TimeUsernameProblemLanguageResultExecution timeMemory
797789amirhoseinfar1385Kangaroo (CEOI16_kangaroo)C++17
51 / 100
120 ms150004 KiB
#include<bits/stdc++.h>
using namespace std;
const int maxn=200+10;
int mod=1e9+7;
long long dp[maxn][maxn][maxn][2];

int ww(long  long a){
	if(a>=mod){
		a-=mod;
	}
	return a;
}

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int n,s,e;
	cin>>n>>s>>e;
	if(s>e){
		swap(s,e);
	}
	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++){
					//if(s==)
					dp[fn][i][j][k]=dp[fn-1][i+1][j][k];
					if(k==0){
						dp[fn][i][j][k]+=dp[j][0][i+fn-1][k];
						dp[fn][i][j][k]+=dp[fn-1][i][j][k^1];
					}
					else{
						dp[fn][i][j][k]+=dp[fn+i-1][0][j][k^1];
						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]));
			//		cout<<fn<<" "<<i<<" "<<j<<" "<<k<<" "<<dp[fn][i][j][k]<<'\n';
				}
			}
		}
	}
	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;
}
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