manacher
1 #include<cstdio> 2 #include<algorithm> 3 #include<string.h> 4 using namespace std; 5 const int Nmax=110005; 6 char s[Nmax]; 7 8 struct Manacher 9 { 10 11 int maxlen; 12 int id; 13 char str[Nmax*2+10]; 14 int p[Nmax*2+10]; 15 int str_len; 16 void init(char *s) 17 { 18 str[0]='$'; 19 str[1]='#'; 20 int n=strlen(s); 21 for(int i=0;i<n;i++) 22 { 23 str[i*2+2]=s[i]; 24 str[i*2+3]='#'; 25 } 26 str_len=n*2+2; 27 str[str_len]='@'; 28 29 id=0; 30 maxlen=0; 31 } 32 int get() 33 { 34 for(int i=2;i<str_len-1;i++) 35 { 36 if(p[id]+id>i) 37 p[i]=min( p[id]+id-i , p[id*2-i] ); 38 else 39 p[i]=1; 40 while( str[ i+p[i] ] == str[ i-p[i] ]) 41 p[i]++; 42 if(p[i]+i>p[id]+id) 43 id=i; 44 if(p[i]>maxlen) 45 maxlen=p[i]; 46 } 47 return maxlen-1; 48 } 49 50 51 }manacher; 52 53 int main() 54 { 55 while(scanf("%s",s)!=EOF) 56 { 57 manacher.init(s); 58 printf("%d ",manacher.get()); 59 } 60 return 0; 61 }