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Cod sursa(job #446499)
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <ctime>
#define FIN "pscpld.in"
#define FOUT "pscpld.out"
#define NMAX 1000010
using namespace std;
char sz[NMAX];
int lg[NMAX * 2], dim = 0;
int main()
{
long long ret = 0;
int tmp, i, l, r, il, ir;
char c;
FILE *fin = freopen(FIN, "r", stdin), *fout = freopen(FOUT, "w", stdout);
for (c = getchar(); c >= 'a' && c <= 'z'; c = getchar()) sz[++dim] = c;
for (i = 1; i <= (dim << 1) - 1; i += 2) lg[i] = 1;
for (i = 1, l, r; i <= (dim << 1) - 1; ++i)
{
if (i & 1) l = ((i + 1) >> 1) - ((lg[i] + 1) >> 1) , r = ((i + 1) >> 1) + ((lg[i] + 1) >> 1);
else l = (i - lg[i]) >> 1, r = ((i + lg[i]) >> 1) + 1;
tmp = l;
while (l && (r - dim - 1))
if (sz[l] == sz[r]) --l, ++r;
else break;
lg[i] += (tmp - l) << 1;
++l; --r;
/*for (il = (l << 1) - 1, ir = (r << 1) - 1; ir - il > 1; ++il, --ir)
if (il & 1) lg[ir] = min(lg[il], min(i - il + 1, il - (l << 1)));
else lg[ir] = min(lg[il], min(i - il + 1, il - (l << 1) + 2));*/
ret += ((long long)lg[i] + 1) >> 1;
}
//brute force
/*for (int i = 1, l, r; i <= dim; ++i)
{
l = i; r = i;
while (l && (r - dim - 1))
{
if (sz[l] == sz[r]) ++ret, --l, ++r;
else break;
}
l = i - 1; r = i;
while (l && (r - dim - 1))
{
if (sz[l] == sz[r]) ++ret, --l, ++r;
else break;
}
}*/
printf("%lld\n", ret);
return 0;
}