The 15-puzzle has been around for over 100 years; even if you don't know it by that name, you've seen it. It is constructed with 15 sliding tiles, each with a number from 1 to 15 on it, and all packed into a 4 by 4 frame with one tile missing. Let's…

一道关乎人生完整的问题. DBFS的优越:避免了结点膨胀太多. 假设一个状态结点可以扩展m个子结点,为了简单起见,假设每个结点的扩展都是相互独立的. 分析:起始状态结点数为1,每加深一层,结点数An = An-1*m.假如搜索了i层找到终点,那么经过的结点数是O(i^m),如果从两边同时搜索,结点数是O(i^(m/2)). 极端情况,终点完全封闭. DBFS的正确姿势: 图片来源:http://www.cppblog.com/Yuan/archive/2011/02/23/140553.aspx…

不多述,直接上代码,至于康拓展开,以前的文章里有 #include<iostream> #include<cstdio> #include<queue> using namespace std; int fac[]={1,1,2,6,24,120,720,5040,40320,362880};//阶乘表 int dir[4][2]={1,0,0,1,-1,0,0,-1};//方向 int vis[362881]; int kangst,kanged; int t1[3]…

Eight II Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 130000/65536 K (Java/Others)Total Submission(s): 4103    Accepted Submission(s): 878 Problem Description Eight-puzzle, which is also called "Nine grids", comes from an old game. In…

http://acm.hdu.edu.cn/showproblem.php?pid=1043 http://poj.org/problem?id=1077 Eight Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 9173    Accepted Submission(s): 2473 Special Judge Problem D…

http://acm.hdu.edu.cn/showproblem.php?pid=1043 题意:给出一个八数码,求出到达指定状态的路径. 思路:路径寻找问题.在这道题里用到的知识点挺多的.第一次用双向BFS来做. ①双向BFS 在单向BFS的基础上,多建一个从终止状态开始搜索的队列,当然这个时候需要两个vis[]辅助数组,分别记录两个队列的访问情况,当两个队列相遇时即可终止循环. ②康托展开 X=a[n]*(n-1)!+a[n-1]*(n-2)!+...+a[i]*(i-1)!+...+a[…

题目来源: http://poj.org/problem?id=1077 题目大意: 给你一个由1到8和x组成的3*3矩阵,x每次可以上下左右四个方向交换.求一条路径,得到12345678x这样的矩阵.若没有路径,则输出unsolvable. 经典的八数码问题. 这题我用A*算法做的.推荐一篇博客,从大体上介绍了一下启发式算法的代表A*算法: https://www.cnblogs.com/zhoug2020/p/3468167.html 首先就是判重的问题,搜索的状态是九个数(含x),开个九重…

快要NOIP 2016 了,现在已经停课集训了.计划用10天来复习以前学习过的所有内容.首先就是搜索. 八数码是一道很经典的搜索题,普通的bfs就可求出.为了优化效率,我曾经用过康托展开来优化空间,甚至还用过A*来优化时间.不过这道题懒得写了,就一个普普通通的bfs,再加上一个stl 的map就水过了. 首先题目要求有多达10000组数据,依次搜索肯定是不行的,我试过用A*来写,第2组数据就会T掉,所以我们考虑用一个预处理.从末尾状态搜索所有可行的状态,并用一个map来存储答案.然后就很好写了.…

The 15-puzzle has been around for over 100 years; even if you don't know it by that name, you've seen it. It is constructed with 15 sliding tiles, each with a number from 1 to 15 on it, and all packed into a 4 by 4 frame with one tile missing. Let's…

题目链接http://acm.hdu.edu.cn/showproblem.php?pid=4531 吉哥系列故事——乾坤大挪移 Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65535/32768 K (Java/Others)Total Submission(s): 555    Accepted Submission(s): 178 Problem Description 只有进入本次马拉松复赛,你才有机会知道一个秘密:吉哥…