267. Palindrome Permutation II
Given a string s, return all the palindromic permutations (without duplicates) of it.
You may return the answer in any order. If s has no palindromic permutation, return an empty list.
790. Domino and Tromino Tiling
You have two types of tiles: a 2 x 1 domino shape and a tromino shape. You may rotate these shapes.
Given an integer n, return the number of ways to tile an 2 x n board. Since the answer may be very large, return it modulo 109 + 7.
In a tiling, every square must be covered by a tile. Two tilings are different if and only if there are two 4-directionally adjacent cells on the board such that exactly one of the tilings has both squares occupied by a tile.
