string/suffix-array.hpp

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Last update: 2024-09-21 22:51:04+07:00
Include: #include "string/suffix-array.hpp"

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#pragma once
#include "data-structure/sparse-table.hpp"
#include "group/monoid/min.hpp"

/**
 * Author: Teetat T.
 * Date: 2024-06-14
 * Description: Suffix Array.
 */

template<class STR>
struct SuffixArray{
    int n;
    vector<int> sa,isa,lcp;
    SparseTable<MinMonoid<int>> st;
    SuffixArray(){}
    SuffixArray(const STR &s){init(s);}
    void init(const STR &s){
        n=(int)s.size();
        sa=isa=lcp=vector<int>(n+1);
        sa[0]=n;
        iota(sa.begin()+1,sa.end(),0);
        sort(sa.begin()+1,sa.end(),[&](int i,int j){return s[i]<s[j];});
        for(int i=1;i<=n;i++){
            int x=sa[i-1],y=sa[i];
            isa[y]=i>1&&s[x]==s[y]?isa[x]:i;
        }
        for(int len=1;len<=n;len<<=1){
            vector<int> ps(sa),pi(isa),pos(n+1);
            iota(pos.begin(),pos.end(),0);
            for(auto i:ps)if((i-=len)>=0)sa[pos[isa[i]]++]=i;
            for(int i=1;i<=n;i++){
                int x=sa[i-1],y=sa[i];
                isa[y]=pi[x]==pi[y]&&pi[x+len]==pi[y+len]?isa[x]:i;
            }
        }
        for(int i=0,k=0;i<n;i++){
            for(int j=sa[isa[i]-1];j+k<n&&s[j+k]==s[i+k];k++);
            lcp[isa[i]]=k;
            if(k)k--;
        }
        st.init(lcp);
    }
    int get_lcp(int i,int j){
        if(i==j)return n-i;
        auto [l,r]=minmax(isa[i],isa[j]);
        return st.query(l+1,r);
    }
};

#line 2 "data-structure/sparse-table.hpp"

/**
 * Author: Teetat T.
 * Date: 2024-06-12
 * Description: Sparse Table class.
 */

template<class Monoid>
struct SparseTable{
    using T = typename Monoid::value_type;
    int n;
    vector<vector<T>> t;
    SparseTable(){}
    SparseTable(const vector<T> &a){init(a);}
    void init(const vector<T> &a){
        n=(int)a.size();
        int lg=31-__builtin_clz(n);
        t.assign(lg+1,vector<T>(n,Monoid::unit()));
        t[0]=a;
        for(int i=0;i<lg;i++){
            for(int j=0;j+(2<<i)<=n;j++){
                t[i+1][j]=Monoid::op(t[i][j],t[i][j+(1<<i)]);
            }
        }
    }
    T query(int l,int r){
        int lg=31-__builtin_clz(r-l+1);
        return Monoid::op(t[lg][l],t[lg][r-(1<<lg)+1]);
    }
};

#line 2 "group/monoid/min.hpp"

/**
 * Author: Teetat T.
 * Date: 2024-04-14
 * Description: Min Monoid class.
 */

template<class T>
struct MinMonoid{
    using value_type = T;
    static constexpr T op(const T &x,const T &y){return min(x,y);}
    static constexpr T unit(){return numeric_limits<T>::max();}
};

#line 4 "string/suffix-array.hpp"

/**
 * Author: Teetat T.
 * Date: 2024-06-14
 * Description: Suffix Array.
 */

template<class STR>
struct SuffixArray{
    int n;
    vector<int> sa,isa,lcp;
    SparseTable<MinMonoid<int>> st;
    SuffixArray(){}
    SuffixArray(const STR &s){init(s);}
    void init(const STR &s){
        n=(int)s.size();
        sa=isa=lcp=vector<int>(n+1);
        sa[0]=n;
        iota(sa.begin()+1,sa.end(),0);
        sort(sa.begin()+1,sa.end(),[&](int i,int j){return s[i]<s[j];});
        for(int i=1;i<=n;i++){
            int x=sa[i-1],y=sa[i];
            isa[y]=i>1&&s[x]==s[y]?isa[x]:i;
        }
        for(int len=1;len<=n;len<<=1){
            vector<int> ps(sa),pi(isa),pos(n+1);
            iota(pos.begin(),pos.end(),0);
            for(auto i:ps)if((i-=len)>=0)sa[pos[isa[i]]++]=i;
            for(int i=1;i<=n;i++){
                int x=sa[i-1],y=sa[i];
                isa[y]=pi[x]==pi[y]&&pi[x+len]==pi[y+len]?isa[x]:i;
            }
        }
        for(int i=0,k=0;i<n;i++){
            for(int j=sa[isa[i]-1];j+k<n&&s[j+k]==s[i+k];k++);
            lcp[isa[i]]=k;
            if(k)k--;
        }
        st.init(lcp);
    }
    int get_lcp(int i,int j){
        if(i==j)return n-i;
        auto [l,r]=minmax(isa[i],isa[j]);
        return st.query(l+1,r);
    }
};