Cod sursă (job #531358)

#include<fstream>
#include<string.h>
using namespace std;
ifstream in("bart.in");
ofstream out("bart.out");
char s[500001];
int pi[500001];
int main()
{
    int n,i,now;
    in>>s+1;
    n=strlen(s+1);
    for(i=2;i<=n;i++)
    {
        now=pi[i-1];
        while(now>0&&s[now+1]!=s[i])
            now=pi[now];
        if(s[now+1]==s[i])
            now++;
        pi[i]=now;
    }
    for(i=1;i<=n-pi[n];i++)
        out<<s[i];
    return 0;
}