update() retains discounted_reward from previous episodes

[BigBadBurrow]

In the update() method the discounted_reward is always calculated using a gamma of the previous discounted_reward, but there's no break between episodes so the reward from one episode is carried across to the next, which I assume cannot be correct.

Suggest adding terminal_states list to the Memory class, and then setting the discounted_reward = 0 when a new episode starts.

[BigBadBurrow]

Remember, the array is reversed so I think you'd need to set the discounted_reward = 0 first:

            if is_terminal:
                discounted_reward = 0
            discounted_reward = reward + (self.gamma * discounted_reward)
            rewards.insert(0, discounted_reward)

[nikhilbarhate99]

Thanks!