Count subsequences of type a^i b^j c^k

//Given a string s, the task is to count number of subsequences of the form aibjck, where i >= 1, j >=1 and k >= 1.

#include <iostream>
using namespace std;

int main() {
    int i,j,t,n;
    cin>>t;
    while(t--)
    {
        string s;
        cin>>s;
        int a=0,b=0,c=0;
        for(i=0;i<s.length();i++)
        {
            if(s[i]=='a')a=1+2*a;
            else if(s[i]=='b')b=a+2*b;
            else c=b+2*c;
        }
        cout<<c<<endl;
    }
    return 0;
}