ds lab 8 task 4

#include<bits/stdc++.h>
using namespace std;
int hash_fn(string s,int n,int i)
{
    int h=0,j,k;
    for(j=0,k=n-1; j<n,k>=0; j++,k--)
        h+=s[i+j]*pow(10,k);//hash function to calculate h with ascii value of the letter and position in the window
    return h%11;
}
int main()
{
    string txt,pat;
    getline(cin,txt);//to take input with blank spaces
    getline(cin,pat);
    int lenp=pat.size(),i,j,flag=0;
    int lent=txt.size();
    int hp=hash_fn(pat,lenp,0);//calculating hash value for the pattern
    for(i=0; i<=lent-lenp; i++)
    {
        int ht=hash_fn(txt,lenp,i);//calculating hash value for windows from the text
        if(ht==hp)
        {
            for(j=0; j<lenp; j++)
            {
                if(txt[i+j]!=pat[j])//if hash value matches then checking if the letters match
                    break;
            }
            if(j==lenp)
            {
                cout<<"Pattern found at index:"<<i<<endl;//if all the letters match then print
                flag=1;
            }
        }
    }
    if(flag==0)
        cout<<"Pattern not found!"<<endl;
}