Palindrome [Manecher]
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
- 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 ...
- [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 ...
- [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 ...
- [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 ...
- [LeetCode] Palindrome Permutation 回文全排列
Given a string, determine if a permutation of the string could form a palindrome. For example," ...
- [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 ...
- [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. ...
- [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 ...
- [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
- Python自动化运维——系统进程管理模块
Infi-chu: http://www.cnblogs.com/Infi-chu/ 模块:psutil psutil是一个跨平台库,可以很轻松的为我们实现获取系统运行的进程和资源利用率等信息. 功能 ...
- linux c fprintf()
#include<stdio.h> #include<unistd.h> #include<time.h> int main(int argc,char *argv ...
- PS作业
- oracle 认识
有一家叫甲骨文的粮店,老板很严谨,为了防止仓库的粮食在买入卖出的时候发生问题,他制订一套流程,首先进出仓库的每一旦粮食都要求有一个编号(SCN),而且出入库之前必须先放到一个平台上(buffer ca ...
- springmvc基础篇—拆分配置文件
一般来讲,在企业实际项目中通常会将配置文件设置为两个:spring-mvc.xml.beans.xml,各自管各自的内容,方便管理. 一.在src下增加如下配置文件: <?xml version ...
- 用node是踩过的一些坑
1.http.request抓取数据时,response的“data”回调事件返回的数据不完整 问题原因:因为“data"事件返回是chunk,就是说是一块块连续的数据 解决的办法:在”da ...
- flask_sqlalchemy中db.session是如何保持请求间独立的--源码阅读笔记
本文主要是为了验证两个问题: flask处理请求时通过新建线程.进程.协程的区别(顺带一提) flask_sqlalchemy是如何使用db.session使多个请求中保函的改变同一个表的sql操作不 ...
- python 基础篇 06 编码 以及小知识点补充
本节主要内容: 1. is和==的区别2. 编码的问题 ⼀. is和==的区别1. id()通过id()我们可以查看到⼀个变量表⽰的值在内存中的地址 注 ----<<<在pytho ...
- 官方文档 恢复备份指南五 Configuring the RMAN Environment
本章内容: Configuring the Environment for RMAN Backups 配置RMAN环境 Configuring RMAN to Make Backups to a ...
- tcp四次撒手
转自:http://www.cnblogs.com/cy568searchx/p/3711670.html 由于TCP连接是全双工的,因此每个方向都必须单独进行关闭.这个原则是当一方完成它的数据发送任 ...