Submission #209623

#	Time	Username	Problem	Language	Result	Execution time	Memory
209623		thebes	Necklace (Subtask 1-3) (BOI19_necklace1)	C++14	45 / 85	1596 ms	376 KiB

necklace

#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse,sse2,ssse3,sse3,sse4,popcnt,avx,mmx,abm,tune=native")
#include <bits/stdc++.h>
#define DEBUG 1
using namespace std;

namespace output{
    void __(short x){cout<<x;}
    void __(unsigned x){cout<<x;}
    void __(int x){cout<<x;}
    void __(long long x){cout<<x;}
    void __(unsigned long long x){cout<<x;}
    void __(double x){cout<<x;}
    void __(long double x){cout<<x;}
    void __(char x){cout<<x;}
    void __(const char*x){cout<<x;}
    void __(const string&x){cout<<x;}
    void __(bool x){cout<<(x?"true":"false");}
    template<class S,class T>
    void __(const pair<S,T>&x){__(DEBUG?"(":""),__(x.first),__(DEBUG?", ":" "),__(x.second),__(DEBUG?")":"");}
    template<class T>
    void __(const vector<T>&x){__(DEBUG?"{":"");bool _=0;for(const auto&v:x)__(_?DEBUG?", ":" ":""),__(v),_=1;__(DEBUG?"}":"");}
    template<class T>
    void __(const set<T>&x){__(DEBUG?"{":"");bool _=0;for(const auto&v:x)__(_?DEBUG?", ":" ":""),__(v),_=1;__(DEBUG?"}":"");}
    template<class T>
    void __(const multiset<T>&x){__(DEBUG?"{":"");bool _=0;for(const auto&v:x)__(_?DEBUG?", ":" ":""),__(v),_=1;__(DEBUG?"}":"");}
    template<class S,class T>
    void __(const map<S,T>&x){__(DEBUG?"{":"");bool _=0;for(const auto&v:x)__(_?DEBUG?", ":" ":""),__(v),_=1;__(DEBUG?"}":"");}
    void pr(){cout<<"\n";}
    template<class S,class... T>
    void pr(const S&a,const T&...b){__(a);if(sizeof...(b))__(' ');pr(b...);}
}

using namespace output;

typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<int,char> pic;
typedef pair<double,double> pdd;
typedef pair<ld,ld> pld;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int,vi> piv;

#define pb push_back
#define fox(i,x,y) for(int i=(x);i<=(y);i++)
#define foxr(i,x,y) for(int i=(y);i>=(x);i--)

const int MN = 3003;
string s, t;
int n, m, i, hsh[2][MN], pw[MN]={1}, pre[MN], suf[MN], st[MN], len[MN], lo, hi, lim1, lim2, ans, sw, fl, ree, k, sh, mid;
inline int gethsh(int id,int x,int y){return hsh[id][y]-hsh[id][x-1]*pw[y-x+1];}
pii sna; queue<pii> hm;

void solve(int init=0){
    for(int i=1;i<=m;i++)
        hsh[1][i]=hsh[1][i-1]*133+t[i-1]-'a'+1;
    k = min(m,lim2);
    for(int i=n;i>=1;i--){
        if(s[i-1]!=t[m-1]){
            suf[i]=0;
            continue;
        }
        //if(init||i==n){
            hi=min(i,k);
            lo=min(hi,max(0,suf[i+1]-1));
            while(lo<hi){
                mid = (lo+hi)/2;
                if(gethsh(0,i-mid,i)==gethsh(1,m-mid,m)) lo=mid+1;
                else hi=mid;
            }
            suf[i]=lo;
        /*}
        else{
            suf[i]=max(0,suf[i+1]-1);
        }*/
    }
    while(hm.size()) hm.pop();
    for(int i=n;i>=1;i--){
        if(suf[i]) hm.push({suf[i],i});
        while(hm.size()){
            if(hm.front().second-hm.front().first+1>i) hm.pop();
            else break;
        }
        if(hm.size()){
            st[i] = lim2-hm.front().first;
            len[i] = hm.front().second-i+1;
        }
        else len[i] = 0, st[i] = lim2;  
    }
    k = min(m,lim1);
    for(int i=1;i<=n;i++){
        if(s[i-1]!=t[0]){
            pre[i]=0;
            continue;
        }
        hi=min(n-i+1,k);
        lo=min(hi,max(pre[i-1]-1,0));
        while(lo<hi){
            mid = (lo+hi)/2;
            if(gethsh(0,i,i+mid)==gethsh(1,1,1+mid)) lo=mid+1;
            else hi=mid;
        }
        pre[i]=lo;
    }
    while(hm.size()) hm.pop();
    for(int i=1;i<=n;i++){
        if(pre[i]) hm.push({pre[i],i});
        while(hm.size()){
            if(hm.front().second+hm.front().first-1<i) hm.pop();
            else break;
        }
        if(hm.size()){
            len[i] = i-hm.front().second+1;
            if(len[i]+len[i+1]>ans){
                ans = len[i]+len[i+1];
                if(sw) sna = {n-(i+len[i+1]), st[i+1]};
                else sna = {hm.front().second-1, st[i+1]};
            }
        }
    }
}

int main(){
    cin >> s >> t;
    n = s.size(), m = t.size();
    for(i=1;i<MN;i++)
        pw[i]=133*pw[i-1];
    for(i=1;i<=n;i++)
        hsh[0][i]=hsh[0][i-1]*133+s[i-1]-'a'+1;
    lim1 = 0; lim2 = m;
    solve(1);
    for(i=1;i<=m;i++){
        lim1++; lim2--;
        char ch = t.back(); t.erase(t.end()-1);
        t.insert(t.begin(),ch);
        solve();
    }
    for(i=0;i<s.size()/2;i++)
        swap(s[i],s[s.size()-i-1]);
    for(i=1;i<=n;i++)
        hsh[0][i]=hsh[0][i-1]*133+s[i-1]-'a'+1;
    lim1 = 0; lim2 = m; sw = 1;
    solve(1);
    for(i=1;i<=m;i++){
        lim1++; lim2--;
        char ch = t.back(); t.erase(t.end()-1);
        t.insert(t.begin(),ch);
        solve();
    }
    printf("%d\n%d %d\n",ans,sna.first,sna.second);
    return 0;
}

Compilation message (stderr)

necklace.cpp: In function 'int main()':
necklace.cpp:142:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(i=0;i<s.size()/2;i++)
             ~^~~~~~~~~~~

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