题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=1560 DNA sequence Time Limit: 15000/5000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 2999    Accepted Submission(s): 1462 Problem Description The twenty-first centu…

题意:给定一些DNA序列,求一个最短序列能够包含所有序列. 思路:记录第i个序列已经被匹配的长度p[i],以及第i序列的原始长度len[i].则有两个剪枝: 剪枝1:直接取最长待匹配长度.1900ms int h = 0; for(int i = 0; i < n; ++i) { h = max(len[i] - p[i], h); //最大待匹配长度 } 剪枝二:统计每个序列里面四种序列值,并求得每种序列值的最长长度.将四种序列值加起来就是最长待匹配长度.180ms int cal() { /…

DNA sequence Time Limit: 15000/5000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 3503    Accepted Submission(s): 1681 Problem Description The twenty-first century is a biology-technology developing century. We kn…

DNA sequence Time Limit : 15000/5000ms (Java/Other)   Memory Limit : 32768/32768K (Java/Other) Total Submission(s) : 15   Accepted Submission(s) : 7 Font: Times New Roman | Verdana | Georgia Font Size: ← → Problem Description The twenty-first century…

题目: The twenty-first century is a biology-technology developing century. We know that a gene is made of DNA. The nucleotide bases from which DNA is built are A(adenine), C(cytosine), G(guanine), and T(thymine). Finding the longest common subsequence…

题目地址:http://acm.hdu.edu.cn/showproblem.php?pid=1560 BFS题解:http://www.cnblogs.com/crazyapple/p/3218107.html 构造一个串,使得它包含所有的给定DNA序列,并且要求长度最短.采用dfs策略,对于每个串定义1个指针,当全部指针为串尾时判断构造的长度,由于状态空间过大,但是又存在冗余搜索,可以用迭代加深将状态减少.最长待构造长度 + 当前长度 < 迭代的最大深度则直接return,大大减少了状态数.…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=1560 题目大意:给出n个字符串,让你找一个字符串使得这n个字符串都是它的子串,求最小长度. 解题思路:迭代加深搜索,迭代加深搜索,就是限制DFS的深度deep,若搜不到答案,则加深深度,重新搜索,这样就防止了随着深度不断加深而进行的盲目搜索.这题的迭代深度deep以这n个子串中的最长长度作为起点,不断+1,知道找到符合条件的字符串.每次DFS的时候,都要判断一下,当前的深度+最少还有加深的深度是否大…

题目大意:有n个DNA序列,构造一个新的序列,使得这n个DNA序列都是它的子序列,然后输出最小长度. 题解:第一次接触IDA*算法,感觉~~好暴力!!思路:维护一个数组pos[i],表示第i个串该匹配第pos[i]个元素.一共有四种可能,A,C,G,T,依次枚举,如果说A和n个串中的第j个串匹配,就直接就pos[j]++就行了,然后进入下一层,如果说最终没有成功构造,还有进行回溯,所以每一层我们都要维护一个数组来记录pos的值方便回溯. 具体实现和注释都在code中了,应该不难理解. code:…

[学时·II] IDA*算法 ■基本策略■ 如果状态数量太多了,优先队列也难以承受:不妨再回头看DFS-- A*算法是BFS的升级,那么IDA*算法是对A*算法的再优化,同时也是对迭代加深搜索(IDFS)的优化.之前的学习中,已经了解到A*算法通过启发函数达到了有效的优化,而迭代加深搜索则通过限制搜索深度,成功地避免了无止境的向下搜索而无解的情况. 现在学习的IDA*算法则是将前两种结合,限制搜索深度,若当前深度加上启发函数预估值(乐观估算:估计值<=实际值)已经大于深度限制,则终止搜索,然后不…

Problem Description The twenty-first century is a biology-technology developing century. We know that a gene is made of DNA. The nucleotide bases from which DNA is built are A(adenine), C(cytosine), G(guanine), and T(thymine). Finding the longest com…