Submission #265339

#	Time	Username	Problem	Language	Result	Execution time	Memory
265339		TadijaSebez	Sailing Race (CEOI12_race)	C++11	100 / 100	1063 ms	6268 KiB

race

#include <bits/stdc++.h>
using namespace std;
#define pb push_back
void ckmx(int&x,int y){x=max(x,y);}
const int N=505;
vector<int> E[N];
int dp[N][N][2],n,k,tmp[N];
bool was[N][N][2];
int on(int l,int r,int v){
	return (l<=r&&l<=v&&r>=v)||(l>r&&(v<=r||v>=l));
}
int DP(int l,int r,int side){
	if(was[l][r][side])return dp[l][r][side];
	int u=side==0?l:r;
	was[l][r][side]=1;
	int L=side==0?(l==n?1:l+1):l;
	int R=side==1?(r==1?n:r-1):r;
	for(int v:E[u]){
		if(on(l,r,v)){
			ckmx(dp[l][r][side],1+max(DP(L,v,1),DP(v,R,0)));
		}
	}
	return dp[l][r][side];
}
int go[N][N][2],has[N][N];
int main(){
	scanf("%i %i",&n,&k);
	for(int i=1;i<=n;i++){
		while(1){
			int j;
			scanf("%i",&j);
			if(j==0)break;
			E[i].pb(j);
			has[i][j]=1;
		}
	}
	auto nxt=[&](int x){return x==n?1:x+1;};
	auto pre=[&](int x){return x==1?n:x-1;};
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n;j++)tmp[j]=-N;
		tmp[i]=0;
		for(int j=i;;j=nxt(j)){
			go[i][j][0]=tmp[j];
			for(int r:E[j]){
				ckmx(tmp[r],tmp[j]+1);
			}
			if(j==pre(i))break;
		}
		for(int j=1;j<=n;j++)tmp[j]=-N;
		tmp[i]=0;
		for(int j=i;;j=pre(j)){
			go[i][j][1]=tmp[j];
			for(int r:E[j]){
				ckmx(tmp[r],tmp[j]+1);
			}
			if(j==nxt(i))break;
		}
	}
	int ans=-1,idx=0;
	for(int i=1;i<=n;i++){
		int now=DP(i,i==1?n:i-1,0);
		if(now>ans)ans=now,idx=i;
	}
	if(k==1){
		for(int i=1;i<=n;i++)for(int j=1;j<=n;j++)if(i!=j){
			if(go[i][j][0]!=0){
				int r=-1;
				for(int l=nxt(j);l!=i;l=nxt(l))if(has[l][i]){r=l;break;}
				if(r!=-1){
					for(int z=nxt(r);z!=i;z=nxt(z))if(has[j][z]){
						int now=1+go[i][j][0]+1+max(DP(nxt(r),z,1),DP(z,pre(i),0));
						if(ans<now)ans=now,idx=r;
					}
				}
			}
			if(go[i][j][1]!=0){
				int r=-1;
				for(int l=pre(j);l!=i;l=pre(l))if(has[l][i]){r=l;break;}
				if(r!=-1){
					for(int z=pre(r);z!=i;z=pre(z))if(has[j][z]){
						int now=1+go[i][j][1]+1+max(DP(z,pre(r),0),DP(nxt(i),z,1));
						if(ans<now)ans=now,idx=r;
					}
				}
			}
		}
	}
	printf("%i\n%i\n",ans,idx);
	return 0;
}

Compilation message (stderr)

race.cpp: In function 'int main()':
race.cpp:27:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   27 |  scanf("%i %i",&n,&k);
      |  ~~~~~^~~~~~~~~~~~~~~
race.cpp:31:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   31 |    scanf("%i",&j);
      |    ~~~~~^~~~~~~~~

• Subtask 1: 100 / 100