Cod sursă (job #376959)

#include <fstream>
#include <cstring>
using namespace std;
ifstream in ("bart.in");
ofstream out ("bart.out");

const int nmax=500000;

char s[nmax+1];

int pa[nmax+1];

int main()
{
    in>>(s+1);
    int n, k;
    n=strlen(s+1);
    for(int i=2; i<=n; i++)
    {
        if(k && s[i]!=s[k+1])
            k=0;
        if(s[i]==s[k+1])
            k++;
        pa[i]=k;
    }
    int xn=n-pa[n];
    for(int i=1; i<=xn; i++)
        out<<s[i];
    return 0;
}