z.cpp

                            >> Z's Algorithm 
    >>> Resources :

    1.  https://www.youtube.com/watch?v=CpZh4eF8QBw
    2.  https://cp-algorithms.com/string/z-function.html


    >>> Implementation :
         
        void pre(string s,ll *z)
        {
            ll n=s.size();
            z[0]=0;
            ll l=0;
            ll r=0;
            for(ll i=1;i<n;i++)
            {
                if(i>r)
                {
                    l=i;
                    r=i;

                    while(r<n and s[r]==s[r-l])
                    {
                        r++;
                    }

                    z[i]=r-l;
                    r--;
                }
                else
                {
                    ll k=i-l;
                    if(z[k]+i<=r)
                    {
                        z[i]=z[k];
                    }
                    else
                    {
                        l=i;

                        while(r<n and s[r]==s[r-l])
                        {
                            r++;
                        }

                        z[i]=r-l;
                        r--;

                    }
                }
            }
        }
        ll Z(string s1,string s2)
        {
            string s3=s1+"!"+s2;
            ll l=s3.size();
            ll z[l];
            pre(s3,z);
            ll c=0;
            for(ll i=0;i<l;i++)
            {
                if(z[i]==s1.size())
                {
                    c++;
                }
            }
            return c;
        }


    >>> Problems:

        Problem-1: http://codeforces.com/problemset/problem/127/D
        Problem-2: http://codeforces.com/contest/432/problem/D