poj 3974

#include <iostream>
#include <cstdio>
using namespace std;
const int maxn = 1e6+10;
char b[maxn], a[maxn<<1];
int p[maxn<<1];

int main()
{
    int tcase = 0;
    while(scanf("%s", &b[1]) != EOF && b[1] != 'E')
    {
        int i;
        for(i = 1; b[i] != '\0'; i++)
        {
            a[i<<1] = b[i];
            a[(i<<1)+1] = '#';
        }
        a[0] = '?', a[1] = '#';
        int n = i<<1;
        int maxl = 0, maxid = 0, id;
        for(int i = 1; i < n; i++)
        {
            if(maxid > i) p[i] = min(p[2*id-i], maxid-i);
            else p[i] = 1;
            while(a[i-p[i]] == a[i+p[i]]) p[i]++;
            if(maxid < i+p[i]) maxid = i+p[i], id = i;
            if(maxl < p[i]) maxl = p[i];
        }
        printf("Case %d: %d\n", ++tcase, maxl-1);
    }
}