1.can anybody tell why m i failing with some test cases.

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#include <iostream>
#include <memory.h>
#include <vector>
#define mod % 1000000007
using namespace std;
#define ll long long
ll int cal(vector<vector<ll int>>  &dp,vector<ll int> &fact,ll int l,ll int r)
{
    
    ll int len=0;
    ll int odd=0;
    vector<ll int> v(26,0);
    for(int i=0;i<26;i++)
    { len += (dp[r][i]-dp[l-1][i])/2;
      //cout<<"\n len = "<<len;
       v[i]=(dp[r][i]-dp[l-1][i])/2;
       if((dp[r][i]-dp[l-1][i])%2)
          odd++;
    }
     ll int ans=fact[len];
     ll int d=1;
    for(int i=0;i<26;i++)
    {d*=fact[v[i]] % 1000000007; 
     d= d mod;
    }
     ans = (ans*max((ll int)1,odd))mod;
     d= ans/d;
    return d%1000000007;
}
int main() {
     string s;
     cin>>s;
     vector<vector<ll int>>  dp;
     dp.resize(s.size() + 1);
     for(ll int i=0;i<=s.size();i++)
     dp[i].resize(26);  
     
     for(int i=0 ; i < s.size();i++)
         dp[i+1][s[i]-'a']++;
     
     for(ll int i=0;i<26;i++)
     for(ll int j=1;j<=s.size();j++)
        dp[j][i]+=dp[j-1][i]; 
      
    vector<ll int > fact(100001,0);
    fact[0]=1;
    for(int i=1;i<=100000;i++)
        fact[i]=(fact[i-1]*i)mod;
    ll int q;
    cin>>q;
    while(q--)
    {
        ll int l,r;
        cin>>l>>r;
        cout<<cal(dp,fact,l,r)<<endl;
        
    }
    
}

For me last five test cases are showing run time errors. And remaining are working well Can anyone see and tell the mistake what i have done import java.io.; import java.util.; import java.text.; import java.math.; import java.util.regex.*;

public class Solution {

static String str; static BigInteger[] fact=new BigInteger[101]; static void initialize(String s) { // This function is called once before all queries. str=s; fact[0]=new BigInteger("1"); for(int i=1;i<101;i++) { fact[i]=new BigInteger(""+i); fact[i]=fact[i].multiply(fact[i-1]); // System.out.println(fact[i]); }

}

static int answerQuery(int l, int r) {
    // Return the answer for this query modulo 1000000007.
    int[] arr=new int[26];
    String sub=str.substring(l-1,r);
    for(int i=0;i<sub.length();i++)
    {

        arr[sub.charAt(i)%97]++;
    }
    int odd=0,even=0;
    ArrayList<Integer> list=new ArrayList<Integer>();
    for(int i=0;i<26;i++)
    {
        int te=arr[i]/2;
        if(te>0)
        {
              even+=te;
        list.add(te);
        }

        odd+=arr[i]%2;
    }
 BigInteger big=fact[even];
    for(int i=0;i<list.size();i++)
    {
        big=big.divide(fact[list.get(i)]);
    }
    if(odd>0)
    big=big.multiply(BigInteger.valueOf(odd));
    big=big.mod(BigInteger.valueOf(1000000007));
    String ss=big+"";

   return Integer.parseInt(ss); 
}

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    String s = in.next();
    initialize(s);
    int q = in.nextInt();
    for(int a0 = 0; a0 < q; a0++){
        int l = in.nextInt();
        int r = in.nextInt();
        int result = answerQuery(l, r);
        System.out.println(result);
    }
    in.close();
}

}

for (int i = 0; i <= n; i++) {
        for (int j = 0; j < A; j++) {
            cnt[i][j] += cnt[i - 1][j];
        }
    }

cnt[i][j] += cnt[i - 1][j]; in this line what happen when i=0; cnt[0][j]+=cnt[-1][j] as it has a index -1 does it make any sence

it is a editorial solution

could someone tell me, why do we need inverses of factorial...also what is mistake in my code..pls. Code in GFG IDE

https://www.youtube.com/watch?v=cJsNNcQlSPA https://youtu.be/_bRVA5b4sb4

This might help understand the editorial.