Palindrome

Time Limit: 15000MS

Memory Limit: 65536K

Total Submissions: 12214

Accepted: 4583

Description

Andy the smart computer science student was attending an algorithms class when the professor asked the students a simple question, "Can you propose an efficient algorithm to find the length of the largest palindrome in a string?"

A string is said to be a palindrome if it reads the same both forwards and backwards, for example "madam" is a palindrome while "acm" is not.

The students recognized that this is a classical problem but couldn't come up with a solution better than iterating over all substrings and checking whether they are palindrome or not, obviously this algorithm is not efficient at all, after a while Andy raised his hand and said "Okay, I've a better algorithm" and before he starts to explain his idea he stopped for a moment and then said "Well, I've an even better algorithm!".

If you think you know Andy's final solution then prove it! Given a string of at most 1000000 characters find and print the length of the largest palindrome inside this string.

Input

Your program will be tested on at most 30 test cases, each test case is given as a string of at most 1000000 lowercase characters on a line by itself. The input is terminated by a line that starts with the string "END" (quotes for clarity).

Output

For each test case in the input print the test case number and the length of the largest palindrome.

Sample Input

abcbabcbabcba

abacacbaaaab

END

Sample Output

Case 1: 13

Case 2: 6

题解

求解最长回文子串的长度

本来是想练hash的,思路:hash+二分,时间复杂度\(O(T*len*log(len))\),其中T为组数,最大为30,len最大为1e6,肯定是过不了的,但是抱着既然是练习hash的心请,多打几遍也没事.然后就硬着头皮写下去,结果一个上午没有调出来,天衣无缝~~~

然后我含恨而去,学习了manacher,发现挺简单的,想学习的推荐博客super_hyper(真的很好理解,讲得很好)

原代码我一定会调出来的

Code

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#define Min(a,b) (a)<(b)?(a):(b)
#define Max(a,b) (a)>(b)?(a):(b)
#define in(i) (i=read())
using namespace std;
int read() {
int ans=0,f=1; char i=getchar();
while(i<'0' || i>'9') {if(i=='-') f=-1; i=getchar();}
while(i>='0' && i<='9') {ans=(ans<<1)+(ans<<3)+i-'0'; i=getchar();}
return ans*f;
}
int n;
char s[1000010],s_new[2000010];
int p[2000010];
int init() {
int len=strlen(s),j=2;
s_new[0]='$'; s_new[1]='#';
for(int i=0;i<len;i++) {
s_new[j++]=s[i];
s_new[j++]='#';
}
s_new[j]='\0';
return j;
}
int Manacher() {
int len=init();
int max_len=-1,id,mx=0;
for(int i=1;i<len;i++) {
if(i<mx) p[i]=Min(p[2*id-i],mx-i);
else p[i]=1;
while(s_new[i-p[i]]==s_new[i+p[i]]) p[i]++;
if(mx<i+p[i]) {
id=i; mx=i+p[i];
}
max_len=Max(max_len,p[i]-1);
}
return max_len;
}
int main()
{
int cnt=0;
while(1) {
cnt++;
scanf("%s",s);
if(s[0]=='E' && s[1]=='N' && s[2]=='D') break;
printf("Case %d: %d\n",cnt,Manacher());
memset(s,0,sizeof(s));
}
return 0;
}

博主蒟蒻,随意转载.但必须附上原文链接

http://www.cnblogs.com/real-l/

Palindrome [Manecher]的更多相关文章

  1. PALIN - The Next Palindrome 对称的数

    A positive integer is called a palindrome if its representation in the decimal system is the same wh ...

  2. [LeetCode] Longest Palindrome 最长回文串

    Given a string which consists of lowercase or uppercase letters, find the length of the longest pali ...

  3. [LeetCode] Palindrome Pairs 回文对

    Given a list of unique words. Find all pairs of distinct indices (i, j) in the given list, so that t ...

  4. [LeetCode] Palindrome Permutation II 回文全排列之二

    Given a string s, return all the palindromic permutations (without duplicates) of it. Return an empt ...

  5. [LeetCode] Palindrome Permutation 回文全排列

    Given a string, determine if a permutation of the string could form a palindrome. For example," ...

  6. [LeetCode] Palindrome Linked List 回文链表

    Given a singly linked list, determine if it is a palindrome. Follow up: Could you do it in O(n) time ...

  7. [LeetCode] Shortest Palindrome 最短回文串

    Given a string S, you are allowed to convert it to a palindrome by adding characters in front of it. ...

  8. [LeetCode] Palindrome Partitioning II 拆分回文串之二

    Given a string s, partition s such that every substring of the partition is a palindrome. Return the ...

  9. [LeetCode] Palindrome Partitioning 拆分回文串

    Given a string s, partition s such that every substring of the partition is a palindrome. Return all ...

随机推荐

  1. JavaScript 转载

    JavaScript概述 ECMAScript和JavaScript的关系 1996年11月,JavaScript的创造者--Netscape公司,决定将JavaScript提交给国际标准化组织ECM ...

  2. Python学习手册之数据类型

    在上一篇文章中,我们介绍了 Python 的异常和文件,现在我们介绍 Python 中的数据类型. 查看上一篇文章请点击:https://www.cnblogs.com/dustman/p/99799 ...

  3. Go语言的标准net库使用

    Go语言的标准net库使用 与大多数语言一样,Go的标准库是很全的,因为Go的出现本来就是为了网络通信的高并发实现,所以其相关的网络库封装得很简洁,也更加的易读.这里对使用到的api进行记录. net ...

  4. 39-Role以及Claims授权

    asp.net core多鼓励使用claims授权 1-使用role授权 在类或方法上贴上Roles,这样就知道有user的角色才可以访问 [Authorize(Roles="user&qu ...

  5. python2.7练习小例子(十五)

        15):题目:输出指定格式的日期.     程序分析:使用 datetime 模块.     程序源代码: #!/usr/bin/python # -*- coding: UTF-8 -*- ...

  6. java练习题——类与对象

    一.请依据代码的输出结果,自行总结Java字段初始化的规律 public static void main(String[] args) { InitializeBlockClass obj=new ...

  7. 一步一步学Linq to sql(三):增删改

    示例数据库 字段名 字段类型 允许空 字段说明 ID uniqueidentifier 表主键字段 UserName varchar(50) 留言用户名 PostTime datetime 留言时间 ...

  8. stm8编程tips(stvd)

    编译完成时显示程序占用的flash和ram大小 将附件压缩包中的mapinfo.exe解压到stvd的安装路径\stvd中 在工程上点右键选settings 右侧的选项卡选择Linker,将categ ...

  9. java二分法来求一个数组中一个值的key

    package TestArray; import java.util.Arrays; /** * 二分法查找 */ public class Test { public static void ma ...

  10. django序列化时间

    具体代码: import json,time,datetime lis ={'time':datetime.date.today(),"username":"zhilei ...