題目網址: http://www.puzzleup.com/2019/
http://www.puzzleup.com/2019/puzzle/?02
答題時限: 08月01日７ＰＭ－比賽結束
加分時限: 08月01日７ＰＭ－08月07日６：５９ＰＭ
答對可得基本分１００分。答案可上傳５次，每改１次答案從基本分扣２０分。　
比賽期間內可隨時上傳答案，加分時限內答對第ｎ天加（６－ｎ）分　 　　 　　
另依題目的難易有額外加分（如有８０％的人這題答錯，答對者加８０分）　　
◆BALL GAME
Your friend will put 100 balls with 5 different colors in a bag and tell
you the number of balls for each color. Then you will randomly choose a
ball and guess its color. Afterr seeing the ball, if your guess is
correct, you will take the ball. If not, then your friend will take the
ball. This game will continue until all the balls are taken. Both of you
try to get as many balls as you can.
What is the maximum number of balls your friend can take?
你朋友將100顆分五種顏色的球放入袋子裡，並告知每種顏色的球數量各為多少。接
下來，你開始隨機選擇一顆球並猜其顏色。然後看球，如果你猜中球的顏色，那顆
球便由你取走。如果沒猜中，則那顆球由你朋友取走。遊戲持續進行至所有球都被
取走為止。你與你朋友雙方都會盡可能地取走更多球。
問你朋友最多能拿到的球有多少？