Update check ab

[tejaswibhagat]

//more optimised way to attempt
bool checkAB(char input[]) {

if (input [0] == '\0')
{
    return true;
}

if (input [0] != 'a')
{
    return false;
}

if (input [1] == 'b' && input [2] == 'b')
{
    return checkAB (input + 3);
}

return checkAB (input + 1);

}