790. 多米诺和托米诺平铺 有两种形状的瓷砖:一种是 2x1 的多米诺形,另一种是形如 "L" 的托米诺形.两种形状都可以旋转. XX <- 多米诺 XX <- "L" 托米诺 X 给定 N 的值,有多少种方法可以平铺 2 x N 的面板?返回值 mod 10^9 + 7. (平铺指的是每个正方形都必须有瓷砖覆盖.两个平铺不同,当且仅当面板上有四个方向上的相邻单元中的两个,使得恰好有一个平铺有一个瓷砖占据两个正方形.) 示例: 输入: 3 输出: 5…
We have two types of tiles: a 2x1 domino shape, and an "L" tromino shape. These shapes may be rotated. XX <- domino XX <- "L" tromino X Given N, how many ways are there to tile a 2 x N board? Return your answer modulo 10^9 + 7. (…
Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers. Ensure that numbers within the set are sorted in ascending order. Example 1…
Given a string S, you are allowed to convert it to a palindrome by adding characters in front of it. Find and return the shortest palindrome you can find by performing this transformation. For example: Given "aacecaaa", return "aaacecaaa&qu…
Given a 2D board and a list of words from the dictionary, find all words in the board. Each word must be constructed from letters of sequentially adjacent cell, where "adjacent" cells are those horizontally or vertically neighboring. The same le…
Design a data structure that supports the following two operations: void addWord(word)bool search(word) search(word) can search a literal word or a regular expression string containing only letters a-z or .. A . means it can represent any one letter.…
There are a total of n courses you have to take, labeled from 0 to n - 1. Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as a pair: [0,1] Given the total number of courses and a l…
