动态规划是一种top-down求解模式,关键在于分解和求解子问题,然后根据子问题的解不断向上递推,得出最终解 因此dp涉及到保存每个计算过的子问题的解,这样当遇到同样的子问题时就不用继续向下求解而直接可以得到结果.状态压缩就是用来保存子问题的解的,主要思想是把所有可能的状态(子问题)用一个数据结构(通常是整数)统一表示,再用map把每个状态和对应结果关联起来,这样每次求解子问题时先find一下,如果map里面已经有该状态的解就不用再求了:同样每次求解完一个状态的解后也要将其放入map中保存 状态…

原题链接 两个人依次从1~maxNum中选取数字(不可重复选取同一个),累和.当一方选取数字累和后结果大于等于给定的目标数字,则此人胜利. 题目给一个maxNum和targetNum,要求判断先手能否胜利. 思路: 首先判断两种特殊条件: 可选最大值大于等于目标值,直接返回true. 其中一个人可选的最大值小于目标值,直接返回false. 具体再看题目,题目给出maxNum不大于20,则可状态压缩为一个int(32位)来保存每个数字是否被使用过(题解中利用1-32位进行存储). 利用一个map存…

In the "100 game," two players take turns adding, to a running total, any integer from 1..10. The player who first causes the running total to reach or exceed 100 wins. What if we change the game so that players cannot re-use integers? For examp…

In the "100 game," two players take turns adding, to a running total, any integer from 1..10. The player who first causes the running total to reach or exceed 100 wins. What if we change the game so that players cannot re-use integers? For examp…

题目链接 864. 获取所有钥匙的最短路径 题意 给定起点,要求在最短步骤内收集完所有钥匙,遇到每把锁之前只有 有对应的钥匙才能够打开 思路 BFS+状态压缩典型题目 先确定起点和总的钥匙数目,其次难点有两处: 如何确定当前路径下已经收集好特定的钥匙 如何确定钥匙已经全部收集完成 第一个问题:可以把每一个节点的状态定义为(x,y,state),其中state为钥匙数目的二进制表示,例如现在收集'b'这把钥匙,那么state更新为2(000010),括号里面为钥匙的二进制数,如果下一轮遇到'B',…

Description Christine and Matt are playing an exciting game they just invented: the Number Game. The rules of this game are as follows. The players take turns choosing integers greater than 1. First, Christine chooses a number, then Matt chooses a nu…

Problem Description In your childhood, people in the famous novel Water Margin, you will win an amazing award. As a smart boy, you notice that to win the award, you must buy much more snacks than it seems to be. To convince your friends not to waste…

Card Collector Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 1708 Accepted Submission(s): 780 Special Judge Problem Description In your childhood, do you crazy for collecting the beautiful cards…

Chess Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 1821    Accepted Submission(s): 799 Problem Description Alice and Bob are playing a special chess game on an n × 20 chessboard. There are se…

Number Game Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 3432 Accepted: 1399 Description Christine and Matt are playing an exciting game they just invented: the Number Game. The rules of this game are as follows. The players take turns…