最长回文串模板题
Manacher 算法
1 #include<cstdio> 2 #include<cstring> 3 #include<algorithm> 4 #include<iostream> 5 #include<cstdlib> 6 #include<string> 7 #include<cmath> 8 #include<vector> 9 using namespace std; 10 const int maxn=1e5+7; 11 const double eps=1e-8; 12 const double pi=acos(-1); 13 #define ll long long 14 #define clc(a,b) memset(a,b,sizeof(a)) 15 16 int Proc(char pszIn[],char pszOut[]) 17 { 18 int nLen=1; 19 pszOut[0]='$'; 20 int i=0; 21 while(pszIn[i]!=' ') 22 { 23 pszOut[nLen++]='#'; 24 pszOut[nLen++]=pszIn[i]; 25 i++; 26 } 27 pszOut[nLen++]='#'; 28 pszOut[nLen]=0; 29 return nLen; 30 } 31 void Manacher(int *p,char *str,int len) 32 { 33 int mx=0,id=0; 34 for(int i=0; i<len; i++) 35 { 36 p[i]=mx>i?min(p[2*id-i],mx-i):1; 37 while(str[i+p[i]]==str[i-p[i]])p[i]++; 38 if(i+p[i]>mx) 39 { 40 mx=i+p[i]; 41 id=i; 42 } 43 } 44 } 45 const int MAXN=220010; 46 char strIn[MAXN]; 47 char strOut[MAXN]; 48 int p[MAXN]; 49 int main() 50 { 51 while(scanf("%s",strIn)!=EOF) 52 { 53 int nLen=Proc(strIn,strOut); 54 Manacher(p,strOut,nLen); 55 int ans=1; 56 for(int i=0; i<nLen; i++) 57 ans=max(ans,p[i]); 58 printf("%d ",ans-1); 59 } 60 return 0; 61 }