Rokua P3805 [Template]manacher algorithm [Manacher]

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Title Description

A string s consisting of a lowercase English character a,b,c...y,z is given, and the length of the longest palindrome in S is obtained.

String length is n

input/output format

Input format:

A line of lowercase English characters a,b,c...y,z a string s

Output format:

An integer representing the answer

input/Output sampleInput Sample # #:

Aaa

Sample # # of output:

3

Description

String length len <= 11000000

Analysis: Manacher algorithm template, algorithm analysis is not specific, five20 big guy speaks very good, can refer to his blog.

Code:

　　

1 //It is made by Holselee on 30th APR 20182 //luogu.org P38053#include <bits/stdc++.h>4 using namespacestd;5 Const intn=2e7+3e6+7;6 CharS[n],neo[n];intP[n];7 intChange ()8 {9   intlen=strlen (s);Ten   intret=0; neo[ret++]='$'; One    for(intI=0; i<len;i++) Aneo[ret++]='#', neo[ret++]=S[i]; -neo[ret++]='#'; neo[++ret]=' /';returnret; - } the intManacher () - { -   intlen=Change (); -   intans=-n,id,mx=0; +    for(intI=1; i<=len;i++){ -     if(I&LT;MX) P[i]=min (p[id*2-i],mx-i); +     Elsep[i]=1; A      while(Neo[i-p[i]]==neo[i+p[i]]) p[i]++; atAns=max (ans,p[i]-1); -     if(I+P[I]&GT;MX) id=i,mx=i+P[i]; -   } -   returnans; - } - intMain () in { -scanf"%s", s); toprintf"%d", Manacher ()); +   return 0; -}

Rokua P3805 [Template]manacher algorithm [Manacher]