Submission #714727

#	Time	Username	Problem	Language	Result	Execution time	Memory
714727		amirhoseinfar1385	Necklace (Subtask 1-3) (BOI19_necklace1)	C++17	5 / 85	508 ms	2388 KiB

necklace

    #include<bits/stdc++.h>
    using namespace std;
    const int maxn=10000;
    int n,m;
    int base=31,mod=1e9+7;
    long long mp[maxn],revmp[maxn];
    long long mypow(long long m,long long y){
    	if(y==0){
    		return 1;
    	}
    	long long p=mypow(m,(y>>1));
    	p*=p;
    	p%=mod;
    	if(y&1){
    		p*=m;
    		p%=mod;
    	}
    	return p;
    }
     
    int main(){
    	ios::sync_with_stdio(0);
    	cin.tie(0);
    	cout.tie(0);	
    	mp[0]=1;
    	for(int i=1;i<maxn;i++){
    		mp[i]=mp[i-1]*base%mod;
    	}
    	revmp[maxn-1]=mypow(mp[maxn-1],mod-2);
    	for(int i=maxn-2;i>=0;i--){
    		revmp[i]=revmp[i+1]*base%mod;
    	}
    	string s,ss;
    	cin>>s>>ss;
    	n=s.size();
    	m=ss.size();
    	vector<int>hashn(n+2),revhashn(n+2),hashm(m+2),revhashm(m+2);	
    	long long unnow=0;
    	for(int i=1;i<=n;i++){
    		hashn[i]=hashn[i-1]+mp[i-1]*s[i-1]%mod;
    		hashn[i]%=mod;
    	}
    	unnow=0;
    	for(int i=n;i>0;i--){
    		revhashn[i]=revhashn[i+1]+mp[n-i]*s[i-1]%mod;
    		revhashn[i]%=mod;
    	}
    	unnow=0;
    	for(int i=1;i<=m;i++){
    		hashm[i]=hashm[i-1]+ss[i-1]*mp[i-1]%mod;
    		hashm[i]%=mod;
    	}
    	unnow=0;
    	for(int i=m;i>0;i--){
    		revhashm[i]=revhashm[i+1]+mp[m-i]*ss[i-1]%mod;
    		revhashm[i]%=mod;
    	}
    	unnow=0;
    	vector<pair<long long ,int>>allh[n+1];
    	for(int i=1;i<=n;i++){
    		for(int j=i;j<=n;j++){
    			long long fake=mod+mod+hashn[j]-hashn[i-1];
    			fake%=mod;
    			fake*=revmp[i-1];
    			fake%=mod;
    			allh[j-i+1].push_back(make_pair(fake,i));
    		//	if(i==4&&j==n){
    		//		cout<<fake<<" 1"<<endl;
    		//	}
    		}
    	}
    	for(int i=0;i<=n;i++){
    		sort(allh[i].begin(),allh[i].end());
    		allh[i].resize(unique(allh[i].begin(),allh[i].end())-allh[i].begin());
    	}
    	pair<int,pair<int,int>>res;
    	res.first=-1;
    	for(int i=1;i<=m;i++){
    		for(int j=i;j<=m;j++){
    			if(j-i+1>n||j-i+1<=res.first){
    				continue;
    			}
    			unnow=0;
    			for(int h=i;h<=j;h++){
    				long long fake=mod+mod+hashm[j]-hashm[h-1];
    				fake%=mod;
    				fake*=revmp[h-1];
    				fake+=(hashm[h]-hashm[i-1]+mod+mod)*revmp[i-1]%mod*mp[j-h+1];
    				fake%=mod;
    				int p=lower_bound(allh[j-i+1].begin(),allh[j-i+1].end(),make_pair(fake,-1))-allh[j-i+1].begin();
    				if(p!=allh[j-i+1].size()&&allh[j-i+1][p].first==fake){
    					res=max(res,make_pair(j-i+1,make_pair(i,allh[j-i+1][p].second)));
    				}
    				fake=mod+mod+revhashm[i]-revhashm[h+1];
    				fake%=mod;
    				fake*=revmp[m-h];
    				fake+=(mod+mod+revhashm[h+1]-revhashm[j+1])*revmp[m-j]%mod*mp[h-i+1]%mod;
    				fake%=mod;
    			//	if(i==3&&j==6&&h==4){
    			//		cout<<fake<<" 2"<<endl;
    			//	}
    				p=lower_bound(allh[j-i+1].begin(),allh[j-i+1].end(),make_pair(fake,-1))-allh[j-i+1].begin();
    				if(p!=allh[j-i+1].size()&&allh[j-i+1][p].first==fake){
    					res=max(res,make_pair(j-i+1,make_pair(i,allh[j-i+1][p].second)));
    				}
    			}
    		}
    	}
    	if(res.first==-1){
    		cout<<-1<<"\n";
    		return 0;
    	}
    	cout<<res.first<<"\n";
    	cout<<res.second.second-1<<" "<<res.second.first-1<<"\n";
    }

Compilation message (stderr)

necklace.cpp: In function 'int main()':
necklace.cpp:91:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   91 |         if(p!=allh[j-i+1].size()&&allh[j-i+1][p].first==fake){
      |            ~^~~~~~~~~~~~~~~~~~~~
necklace.cpp:103:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  103 |         if(p!=allh[j-i+1].size()&&allh[j-i+1][p].first==fake){
      |            ~^~~~~~~~~~~~~~~~~~~~
necklace.cpp:38:16: warning: variable 'unnow' set but not used [-Wunused-but-set-variable]
   38 |      long long unnow=0;
      |                ^~~~~

• Subtask 1: 5 / 25
• Subtask 2: 0 / 20
• Subtask 3: 0 / 40