You need to store the leaves hierarchically, sometimes you will count the leaves. Tree will be a suitable structure to facilitate leaf counting.
Apply singleton to maintain a single phone line between the two sides indefinitely instead of repeatedly establishing and disconnecting multiple phone lines for efficiency.
Having been with you for a long time, your robot has memories that regular manufacturing can't produce, now you want to clone it. Prototype will be your remedy.
As the coach of a strong team, you plan to attack to find a goal and then prioritize possession to preserve the score. This combination is called strategy.
Having ice creams (popsicle, cone) and curious about how good it will be with extra flavor. For the most authentic experience, you should dip your ice creams in each flavor.