Chicken and Egg
Separating egg-laying chickens from non-egg-laying chickens by keeping them in boxes.
Separating egg-laying chickens from non-egg-laying chickens by keeping them in boxes.
Counting the number of ways to make an exact amount using Canadian coins and bills.
“等等,你怎么又写我死掉的故事?”灰灰生气地说。 “啊,真的!一不留神就又选了这样的故事。”小丹不好意思地挠了挠脸。“不过别急,这个王子还是这个故事的主角呢。”
Tiling a long and narrow gridded strip with square tiles.