Submission #348402

#	Time	Username	Problem	Language	Result	Execution time	Memory
348402		Aaeria	Palindromes (APIO14_palindrome)	C++14	73 / 100	201 ms	131072 KiB

palindrome

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/priority_queue.hpp>
//#pragma GCC optimize("Ofast") //#pragma GCC optimize "unroll-loops" //#pragma GCC target "sse,sse2,sse3,sse4,abm,avx,avx2,fma,mmx,popcnt,tune=native" //#pragma GCC optimize "prefetch-loop-arrays"
using namespace std; using namespace __gnu_pbds;
#define foru(i,a,b) for(int i=(a);i<(b);i++)
#define ford(i,a,b) for(int i=(a);i>=(b);i--)
#define fori(a,b) foru(i,a,b)
#define forj(a,b) foru(j,a,b)
#define fork(a,b) foru(k,a,b)
#define seto(x,i) memset(x,i,sizeof x)
#define pf first
#define ps second
#define pb push_back
#define eb emplace_back
#define em emplace
#define mp make_pair
#define mt make_tuple
#define popcount __builtin_popcount
#define popcountll __builtin_popcountll
#define clz __builtin_clz
#define clzll __builtin_clzll
#define ctz __builtin_ctz
#define ctzll __builtin_ctzll
#define P2(x) (1LL<<(x))
#define sz(x) (int)x.size()
#define all(x) begin(x),end(x)
#if __SIZEOF_INT128__
    typedef __int128_t i128; typedef __uint128_t ui128;
#else
    typedef int64_t i128; typedef uint64_t ui128;
#endif
typedef int64_t ll;  typedef uint64_t ull; typedef int8_t byte; typedef long double lld; typedef string str;
typedef pair<int,int> pii; typedef pair<ll,ll> pll; typedef pair<lld,lld> pdd;
template<class T1,class T2> using ordered_map=tree<T1,T2,less<T1>,rb_tree_tag,tree_order_statistics_node_update>; template<class T1> using ordered_set=ordered_map<T1,null_type>;
template<class T> using minpq=std::priority_queue<T,vector<T>,greater<T>>; template<class T> using maxpq=std::priority_queue<T,vector<T>,less<T>>;
template<class T> using minpairingheap=__gnu_pbds::priority_queue<T,greater<T>,pairing_heap_tag>; template<class T>using maxpairingheap=__gnu_pbds::priority_queue<T,less<T>,pairing_heap_tag>;
const int inf=0x3f3f3f3f,MOD=1e9+7; const ll INF=0x3f3f3f3f3f3f3f3f; const lld PI=acos((lld)-1);
const ll SEED=443214^chrono::duration_cast<chrono::nanoseconds>(chrono::high_resolution_clock::now().time_since_epoch()).count();
mt19937 randgen(SEED); int randint(int a, int b){return uniform_int_distribution<int>(a,b)(randgen);} ll randll(ll a, ll b){return uniform_int_distribution<ll>(a,b)(randgen);}
ll gcd(ll a, ll b){return b?gcd(b,a%b):a;}
ll fpow(ll a,ll b){ll ret=1;for(;b;b>>=1){if(b&1) ret=ret*a%MOD;a=a*a%MOD;}return ret;}
template<class T1,class T2>constexpr const auto _min(const T1&x,const T2&y){return x<y?x:y;} template<class T,class...Ts>constexpr auto _min(const T&x,const Ts&...xs){return _min(x,_min(xs...));}
template<class T1,class T2>constexpr const auto _max(const T1&x,const T2&y){return x>y?x:y;} template<class T,class...Ts>constexpr auto _max(const T&x,const Ts&...xs){return _max(x,_max(xs...));}
#define min(...) _min(__VA_ARGS__)
#define max(...) _max(__VA_ARGS__)
template<class T1,class T2>constexpr const bool ckmin(T1&x,const T2&y){return x>y?x=y,1:0;} template<class T,class...Ts>constexpr bool ckmin(T&x,const Ts&...xs){return ckmin(x,_min(xs...));}
template<class T1,class T2>constexpr const bool ckmax(T1&x,const T2&y){return x<y?x=y,1:0;} template<class T,class...Ts>constexpr bool ckmax(T&x,const Ts&...xs){return ckmax(x,_max(xs...));}
struct chash{
    static ll splitmix64(ll x){x+=0x9e3779b97f4a7c15; x=(x^(x>>30))*0xbf58476d1ce4e5b9; x=(x^(x>>27))*0x94d049bb133111eb; return x^(x>>31);}
    template<class T> size_t operator()(const T &x) const{return splitmix64(hash<T>()(x)+SEED);}
    template<class T1,class T2> size_t operator()(const pair<T1,T2>&x)const{return 31*operator()(x.first)+operator()(x.second);}};
void fileIn(string s){freopen(s.c_str(),"r",stdin);} void fileOut(string s){freopen(s.c_str(),"w",stdout);} void fileIO(string s){fileIn(s+".in"); fileOut(s+".out");}
string to_string(char c){return string(1,c);} string to_string(char* s){return (string)s;} string to_string(string s){return s;}
template<class T> string to_string(complex<T> c){stringstream ss; ss<<c; return ss.str();} template<class T1,class T2> string to_string(pair<T1,T2> p){return "("+to_string(p.pf)+","+to_string(p.ps)+")";}
template<size_t SZ> string to_string(bitset<SZ> b){string ret=""; fori(0,SZ) ret+=char('0'+b[i]); return ret;}
template<class T> string to_string(T v){string ret="{"; for(const auto& x:v) ret+=to_string(x)+","; return ret+"}";}
void DBG(){cerr<<"]"<<endl;} template<class T,class... Ts> void DBG(T x,Ts... xs){cerr<<to_string(x); if(sizeof...(xs)) cerr<<", "; DBG(xs...);}
#ifdef LOCAL_PROJECT
    #define dbg(...) cerr<<"Line("<< __LINE__<<") -> ["<<#__VA_ARGS__<<"]: [", DBG(__VA_ARGS__)
#else
    #define dbg(...) 0
#endif
#define nl "\n"

const int N=600010,M=MOD;
int n,oc[N],pal[N],num[N],x,last,rt[N];
ll ans;
maxpq<int> len[N];
struct node{
    int len,p,nxt[26];
};
struct SuffixAutomaton{
    int last;
    vector<node> st;
    void init(string s){
        st.clear(); last=0; st.emplace_back(); st[0].p=-1;
        for(auto i:s) ins(i-'a');
    }
    void ins(int c){
        int cur=st.size(),p=last; st.emplace_back(); oc[cur]=1;
        st[cur].len=st[last].len+1;
        if(st[cur].len) num[st[cur].len-1]=cur;
        while(p!=-1&&!st[p].nxt[c]){
            st[p].nxt[c]=cur;
            p=st[p].p;
        }
        if(p==-1) st[cur].p=0;
        else{
            int q=st[p].nxt[c];
            if(st[q].len==st[p].len+1) st[cur].p=q;
            else{
                int clone=st.size(); st.pb(st[q]);
                st[clone].len=st[p].len+1;
                while(p!=-1&&st[p].nxt[c]==q){
                    st[p].nxt[c]=clone;
                    p=st[p].p;
                }
                st[q].p=st[cur].p=clone;
            }
        }
        last=cur;
    }
} sa;
str s;
vector<int> gr[N];
char in[N];
int szdfs(int v){
    for(auto i:gr[v]) oc[v]+=szdfs(i);
    return oc[v];
}
void dfs(int v){
    rt[v]=v;
    for(auto i:gr[v]){
        dfs(i);
        for(;sz(len[rt[i]])&&len[rt[i]].top()>sa.st[v].len;len[rt[i]].pop()) ckmax(ans,1LL*len[rt[i]].top()*oc[i]);
        if(sz(len[rt[i]])>sz(len[rt[v]])) swap(rt[i],rt[v]);
        for(;sz(len[rt[i]]);len[rt[i]].pop()) len[rt[v]].em(len[rt[i]].top());
    }
}

int main(){
    cin.tie(0)->sync_with_stdio(0);
    cin>>s; n=sz(s); sa.init(s);
    fori(1,sz(sa.st)) gr[sa.st[i].p].pb(i);
    szdfs(0);
    in[n*2]='#';
    fori(0,n){
        in[i*2+1]=s[i]; in[i*2]='#';
    }
    n=n*2+1;
    fori(1,n){
        for(pal[i]=i>=x? 1: min(x-i,pal[last*2-i]);i-pal[i]>=0&&i+pal[i]<n&&in[i-pal[i]]==in[i+pal[i]];pal[i]++);
        if(i+pal[i]>x) x=i+pal[i],last=i;
    }
    fori(1,n-1){
        pal[i]--;
        dbg((i-pal[i])/2,(i+pal[i]-2)/2);
        len[num[(i+pal[i]-2)/2]].em((i+pal[i]-2)/2-(i-pal[i])/2+1);
    }
    dfs(0);
    cout<<ans;
    return 0;
}
/**
overflow

pal[i]--
i-pal[i]+1 , i+pal[i]-1


(i+pal[i]-2)/2
*/

Compilation message (stderr)

palindrome.cpp: In function 'int main()':
palindrome.cpp:63:22: warning: statement has no effect [-Wunused-value]
   63 |     #define dbg(...) 0
      |                      ^
palindrome.cpp:139:9: note: in expansion of macro 'dbg'
  139 |         dbg((i-pal[i])/2,(i+pal[i]-2)/2);
      |         ^~~
palindrome.cpp: In function 'void fileIn(std::string)':
palindrome.cpp:54:30: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   54 | void fileIn(string s){freopen(s.c_str(),"r",stdin);} void fileOut(string s){freopen(s.c_str(),"w",stdout);} void fileIO(string s){fileIn(s+".in"); fileOut(s+".out");}
      |                       ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
palindrome.cpp: In function 'void fileOut(std::string)':
palindrome.cpp:54:84: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   54 | void fileIn(string s){freopen(s.c_str(),"r",stdin);} void fileOut(string s){freopen(s.c_str(),"w",stdout);} void fileIO(string s){fileIn(s+".in"); fileOut(s+".out");}
      |                                                                             ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 26 / 26
• Subtask 5: 0 / 27