poj 3974 Palindrome

namacher裸题++

#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <iostream>
#define LL long long
using namespace std;

const int maxn=2333333;

char s[maxn<<1],a[maxn];
int len[maxn<<1];

int manachar(char *p)
{
    int l=0,n=strlen(p);
    s[l++]='$'; s[l++]='#';
    for (int i=0; i<n; i++) s[l++]=p[i],s[l++]='#';
    s[l++]='&'; s[l]=0;
    int mx=0,pos=0,ans=0;
    for (int i=1; i<l; i++)
    {
        if (mx>i) len[i]=min(len[pos*2-i],mx-i); else len[i]=1;
        while (s[i+len[i]]==s[i-len[i]]) len[i]++;
        ans=max(ans,len[i]);
        if (len[i]+i>mx) mx=i+len[i],pos=i;
    }
    return ans-1;
}

int main()
{
    int T=0;
    while (scanf("%s",a)!=EOF)
    {
        if (a[0]=='E') break;
        printf("Case %d: %d
",++T,manachar(a));
    }
    return 0;
}