"We can show the main effect by plotting the mean of the `beer` group and the mean of the `water` group, as shown on the graph below. The black dashed line shows the difference between the overall ...

Given a string s, return all the palindromic permutations (without duplicates) of it. Return an empty list if no palindromic permutation could be form. 先用map來整理出所有char的個數，檢查一下char是否有兩個以上的奇數，若是的話 ...