Manacher模板

Manacher模板

求最长回文子串。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<vector>
#include<stack>
#include<queue>
#include<set>
#include<map>
#include<string>
#include<math.h>
#include<cctype>
#define ll long long
#define REP(i,a,b) for(int (i)=(a);(i)<=(b);(i)++)
#define REPP(i,a,b,t) for(int (i)=(a);(i)<=(b);(i)+=(t))
#define rep(i,a,b) for(int (i)=(a);(i)>=(b);(i)--)
#define repp(i,a,b,t) for(int (i)=(a);(i)>=(b);(i)-=(t))
#define PII pair<int,int>
#define fst first
#define snd second
#define MP make_pair
#define PB push_back
#define RI(x) scanf("%d",&(x))
#define RII(x,y) scanf("%d%d",&(x),&(y))
#define RIII(x,y,z) scanf("%d%d%d",&(x),&(y),&(z))
#define DRI(x) int (x);scanf("%d",&(x))
#define DRII(x,y) int (x),(y);scanf("%d%d",&(x),&(y))
#define DRIII(x,y,z) int (x),(y),(z);scanf("%d%d%d",&(x),&(y),&(z))
#define RS(x) scanf("%s",x)
#define RSS(x,y) scanf("%s%s",x,y)
#define DRS(x) char x[maxn];scanf("%s",x)
#define DRSS(x,y) char x[maxn],y[maxn];scanf("%s%s",x,y)
#define MS0(a) memset((a),0,sizeof((a)))
#define MS1(a) memset((a),-1,sizeof((a)))
#define MS(a,b) memset((a),(b),sizeof((a)))
#define ALL(v) v.begin(),v.end()
#define SZ(v) (int)(v).size()

using namespace std;

const int maxn=5000100;
const int INF=(1<<29);
const double EPS=0.0000000001;
const double Pi=acos(-1.0);

char s[maxn],t[maxn];
int p[maxn];

int Manacher(char *s)
{
    int len=strlen(s);
    REP(i,0,len) t[2*i]='#',t[2*i+1]=s[i];
    len=strlen(t);
    int id=0,R=0;
    MS0(p);
    REP(i,0,len-1){
        if(id+p[id]<i){
            int r=0;
            while(i-r>=0&&i+r<len&&t[i-r]==t[i+r]) r++;
            p[i]=r-1;
        }
        else{
            int k=i-id;
            if(id-p[id]>id-k-p[id-k]) p[i]=id-k-(id-p[id]);
            else if(id-p[id]<id-k-p[id-k]) p[i]=p[id-k];
            else{
                int r=p[id-k];
                while(i-r>=0&&i+r<len&&t[i-r]==t[i+r]) r++;
                p[i]=r-1;
            }
        }
        if(p[i]>R) R=p[i];
        if(i+p[i]>id+p[id]) id=i;
    }
    return R;
}

int main()
{
    freopen("in.txt","r",stdin);
    int casen=1;
    while(RS(s)&&strcmp(s,"END")){
        printf("Case %d: %d
",casen++,Manacher(s));
    }
    return 0;
}