题目:http://acm.hdu.edu.cn/showproblem.php?pid=5297 题意:给定整数n和整数r,在1.2.3.4.5.......的序列中删掉能够开2次方的数,3次方的数,4次方的数,.......r次方的数,剩下的数称为Y序列,求Y序列中第n个数是多少. 分析:对于一个数x,假设求出x在Y序列的位置就好办了. 先无论序列中的1,假如r=3,能够开2次方的数有4,9,16,25,36,49,64..... 能够开3次方的数有8,27,64....... 我们把能够开…

Yellowstar likes integers so much that he listed all positive integers in ascending order,but he hates those numbers which can be written as a^b (a, b are positive integers,2<=b<=r),so he removed them all.Yellowstar calls the sequence that formed by…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=5297 题意:给你一个所有正整数的序列,然后去掉满足x^(2~r)的所有数(x为所有正整数,r>=2题目给出),问你现在这个序列的第n个数是什么 解:首先想到写一个函数func(y),它可以计算出给定数字y是序列中第几个数,这样我们大概可以二分答案~(事实上会TLE,得用迭代法,当然迭代的话也是用这个函数) 那么如何实现func: 首先想去掉满足x^2的所有数,我们可以用pow(y, 1/2)计算出y…

Y sequence 题目连接: http://acm.hdu.edu.cn/showproblem.php?pid=5297 Description Yellowstar likes integers so much that he listed all positive integers in ascending order,but he hates those numbers which can be written as a^b (a, b are positive integers,2…

Y sequence Problem's Link: http://acm.hdu.edu.cn/showproblem.php?pid=5297 Mean: 有连续数列A={1,2,3,4,5,6,7,8 .....},将可以表示成a^b次方的数删除,a={1,2,3,4,5...},而2<=b<=r,删除后形成一个新的数列,求这个数列的第n项. analyse: 很有趣的一道数论题. 对于给定的一个n,如果我们知道1~n中被删除的数字为k个,那么答案一定大于等于n+k,所以向后至少移动k个…

Y sequence Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 667    Accepted Submission(s): 147 Problem Description Yellowstar likes integers so much that he listed all positive integers in ascend…

Number Sequence Time Limit: 10000/3000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others) Problem Description Given a number sequence b1,b2…bn. Please count how many number sequences a1,a2,...,an satisfy the condition that a1*a2*...*an=b1*…

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 betw…

题意:给定正整数n和r.定义Y数列为从正整数序列中删除全部能表示成a^b(2 ≤ b ≤ r)的数后的数列,求Y数列的第n个数是多少. 比如n = 10. r = 3,则Y数列为2 3 5 6 7 10 11 12 13 14,第10个数是14. 非常有趣的一道数论题.题目给出的范围是long long范围的. 所以显然不用去枚举每一个数了,更不用说推断每一个数是不是某个数的某次方.那么这个题怎么下手呢.首先我们能够非常直观的想到,被删去的数显然是非常分散的.由于能表示成某个数的幂这种形式的数非…

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.…