上周电面的Citadel NXT，面试官简短介绍了一下公司，就开始了coding interview。题目很经典，LRU Cache

我考了这题没做出来

Given 3n people that the i-th person can pass a test with probability p_i,

now you are required to divide them to n groups that each group has 3 people.

The score of one group equals 1 if at least two people pass the test, 0 otherwise.

In order to maximize the expectation of total score, how do you group them?

感觉得用 Integer programming，没法直接算