抽袜子保证同色一双
Matching Socks
题目详情
抽屉里有 2 只红袜子、20 只黄袜子、31 只蓝袜子。
不看颜色随机抽取。问：至少抽多少只才能保证一定抽到同色的一双？
You have 2 red socks, 20 yellow socks, and 31 blue socks in a drawer. What is the minimum number of socks you must pull out (without looking) to guarantee a pair of the same color?
解析
需要 4 只。
最坏情况前 3 只分别是红、黄、蓝三种不同颜色，第 4 只必然与其中某一种同色。
Original Explanation
You need 4 socks. In the worst case, you get 3 different colors with the first 3 socks, so the 4th sock must match one of those colors.