Light OJ: 1255 – Substring Frequency(Hash)

Problem Link : http://lightoj.com:81/volume/problem/1255


#include <bits/stdc++.h>

#define pii              pair <int,int>
#define pll              pair <long long,long long>
#define sc               scanf
#define pf               printf
#define Pi               2*acos(0.0)
#define ms(a,b)          memset(a, b, sizeof(a))
#define pb(a)            push_back(a)
#define MP               make_pair
#define db               double
#define ll               long long
#define EPS              10E-10
#define ff               first
#define ss               second
#define sqr(x)           (x)*(x)
#define D(x)             cout<<#x " = "<<(x)<<endl
#define VI               vector <int>
#define DBG              pf("Hi\n")
#define MOD              1000000007
#define CIN              ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define SZ(a)            (int)a.size()
#define sf(a)            scanf("%d",&a)
#define sfl(a)           scanf("%lld",&a)
#define sff(a,b)         scanf("%d %d",&a,&b)
#define sffl(a,b)        scanf("%lld %lld",&a,&b)
#define sfff(a,b,c)      scanf("%d %d %d",&a,&b,&c)
#define sfffl(a,b,c)     scanf("%lld %lld %lld",&a,&b,&c)
#define stlloop(v)       for(__typeof(v.begin()) it=v.begin();it!=v.end();it++)
#define loop(i,n)        for(int i=0;i<n;i++)
#define loop1(i,n)       for(int i=1;i<=n;i++)
#define REP(i,a,b)       for(int i=a;i<b;i++)
#define RREP(i,a,b)      for(int i=a;i>=b;i--)
#define TEST_CASE(t)     for(int z=1;z<=t;z++)
#define PRINT_CASE       printf("Case %d: ",z)
#define CASE_PRINT       cout<<"Case "<<z<<": "
#define all(a)           a.begin(),a.end()
#define intlim           2147483648
#define infinity         (1<<28)
#define ull              unsigned long long
#define gcd(a, b)        __gcd(a, b)
#define lcm(a, b)        ((a)*((b)/gcd(a,b)))

using namespace std;


/*----------------------Graph Moves----------------*/
//const int fx[]={+1,-1,+0,+0};
//const int fy[]={+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
/*------------------------------------------------*/

/*-----------------------Bitmask------------------*/
//int Set(int N,int pos){return N=N | (1<<pos);}
//int reset(int N,int pos){return N= N & ~(1<<pos);}
//bool check(int N,int pos){return (bool)(N & (1<<pos));}
/*------------------------------------------------*/

/*---------------------Hashing---------------------*/

#define MH 1000006

#define Base1 10000019
#define Base2 10000079

#define MOD1 1000000007
#define MOD2 1000000009

ll B1[MH],B2[MH];

void init_hash()
{
    B1[0]=B2[0]=1;
    for(int i=1;i<MH;i++)
    {
        B1[i]=(B1[i-1]*Base1)%MOD1;
        B2[i]=(B2[i-1]*Base2)%MOD2;
    }
}

struct Hash
{
    pll H[MH];
    int digit[MH];
    int len;

    Hash()
    {
        len=0;
        H[0]=pll(0,0);
    }

    void clear()
    {
        len=0;
        H[0]=pll(0,0);
    }

    void insert(char ch)
    {
        len++;
        digit[len]=ch-'a'+1;
        H[len].ff=(((H[len-1].ff*Base1)%MOD1)+digit[len])%MOD1;
        H[len].ss=(((H[len-1].ss*Base2)%MOD2)+digit[len])%MOD2;
    }

    pll substr(int l, int r)
    {
        int sub_len=r-l+1;
        pll ans;
        ans.ff=(H[r].ff-((H[l-1].ff*B1[sub_len])%MOD1)+MOD1)%MOD1;
        ans.ss=(H[r].ss-((H[l-1].ss*B2[sub_len])%MOD2)+MOD2)%MOD2;
        return ans;
    }

    pll concate(pll h, int l, int r)
    {
        pll x=substr(l,r);
        int sub_len=r-l+1;
        h.ff=(((h.ff*B1[sub_len])%MOD1)+x.ff)%MOD1;
        h.ss=(((h.ss*B2[sub_len])%MOD2)+x.ss)%MOD2;
        return h;
    }

    bool operator==(const Hash& p) const
    {
        return len==p.len && H[len]==p.H[len];
    }

    pll & operator[](int index)
    {
        return H[index];
    }
};

Hash h1,h2;

int lcp(int id1, int id2, int l)
{
    int lo=1,hi=l;
    while(lo<=hi)
    {
        int mid=(lo+hi)/2;
        if(h1.substr(id1,id1+mid)==h2.substr(id2,id2+mid))
            lo=mid+1;
        else
            hi=mid-1;
    }
    return hi;
}

/*------------------Hashing End---------- ----------*/

char text[MH],pattern[MH];

int main()
{

    ///freopen("in.txt","r",stdin);
    ///freopen("out.txt","w",stdout);

    init_hash();
    int t;
    sf(t);
    getchar();

    TEST_CASE(t)
    {
        sc("%s %s",text,pattern);
        int l1=strlen(text);
        int l2=strlen(pattern);

        h1.clear();
        h2.clear();

        for(int i=0;i<l1;i++)
            h1.insert(text[i]);
        for(int i=0;i<l2;i++)
            h2.insert(pattern[i]);
        int ans=0;

        for(int i=0;i<=l1-l2;i++)
        {
            if(h1.substr(i+1,i+l2)==h2[l2])
                ans++;
        }

        PRINT_CASE;
        pf("%d\n",ans);


    }

    return 0;
}


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