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| #include <bits/stdc++.h>
#define LL long long
using namespace std;
const int Maxn = 100000 + 100;
int S[Maxn];
char S1[Maxn];
LL Sum[Maxn];
int cnt;
struct tree
{
int cnt, ch[30], len, fail;
};
namespace PAM
{
tree Tree[Maxn];
int root0, root1, now, n;
inline void init ()
{
memset(Tree, 0, sizeof Tree);
memset(S, -1, sizeof S);
n = 0;
cnt = -1;
now = 0;
root0 = ++cnt, root1 = ++cnt;
S[0] = -1;
Tree[root0].fail = root1;
Tree[root0].len = 0;
Tree[root1].len = -1;
}
inline int get_fail (int now)
{
while (S[n - Tree[now].len - 1] != S[n]) now = Tree[now].fail;
return now;
}
inline int add (int c)
{
S[++n] = c;
now = get_fail(now);
if (!Tree[now].ch[c])
{
int x = ++cnt;
Tree[x].len = Tree[now].len + 2;
Tree[x].fail = Tree[get_fail(Tree[now].fail)].ch[c];
Tree[x].cnt = Tree[Tree[x].fail].cnt + 1;
Tree[now].ch[c] = x;
}
now = Tree[now].ch[c];
return Tree[now].cnt;
}
}
int main()
{
#ifdef hk_cnyali
freopen("A.in", "r", stdin);
freopen("A.out", "w", stdout);
#endif
while (~scanf("%s", S1))
{
PAM :: init();
int N = strlen(S1);
Sum[N] = 0;
for (int i = N - 1; i >= 0; --i)
Sum[i] = Sum[i + 1] + (LL)PAM :: add(S1[i] - 'a' + 1);
PAM :: init();
LL Ans = 0;
for (int i = 0; i < N; ++i)
Ans += (LL)((LL)PAM :: add(S1[i] - 'a' + 1) * Sum[i + 1]);
cout<<Ans<<endl;
}
return 0;
}
3.16 Upd
--------
今天无聊把A题manacher魔改一番A掉了这道题 原来用manacher做这道题更简单
#include <bits/stdc++.h>
#define int long long
using namespace std;
const int Maxn = 2e5 + 10 ;
char S[Maxn], A[Maxn];
int P[Maxn];
int Sum1[Maxn], Sum2[Maxn];
int L[Maxn], R[Maxn];
int N;
inline void Init ()
{
memset(P, 0, sizeof P);
memset(A, 0, sizeof A);
memset(L, 0, sizeof L);
memset(R, 0, sizeof R);
memset(Sum1, 0, sizeof Sum1);
memset(Sum2, 0, sizeof Sum2);
}
inline void Manacher ()
{
N = strlen(S + 1);
for (int i = 1; i <= N; ++i)
A[i * 2] = S[i], A[i * 2 - 1] = '#';
A[0] = '%', A[N * 2 + 1] = '#';
N = N * 2 + 1;
for (int i = 0; i <= N; ++i) S[i] = A[i];
int id = 0, Max = 0;
for (int i = 1; i <= N; ++i)
{
if (i < Max)
P[i] = min(P[2 * id - i], Max - i);
else P[i] = 1;
while (S[i + P[i]] == S[i - P[i]]) P[i] ++;
if (Max < i + P[i] - 1)
{
Max = i + P[i] - 1;
id = i;
}
}
}
inline void Solve ()
{
Manacher();
for (int i = 1; i <= N; ++i)
Sum1[i - P[i] + 1] += 1, Sum1[i + 1] -= 1;
for (int i = 1; i <= N; ++i)
{
Sum1[i] += Sum1[i - 1];
if (!(i % 2)) L[i / 2] = Sum1[i];
}
memset(Sum1, 0, sizeof Sum1);
for (int i = 1; i <= N; ++i)
Sum1[i] += 1, Sum1[i + P[i]] -= 1;
for (int i = 1; i <= N; ++i)
{
Sum1[i] += Sum1[i - 1];
if (!(i % 2)) R[i / 2] = Sum1[i];
}
memset(Sum2, 0, sizeof Sum2);
N /= 2;
for (int i = N; i >= 1; --i)
Sum2[i] = Sum2[i + 1] + L[i];
int Ans = 0ll;
for (int i = 1; i < N; ++i)
(Ans += Sum2[i + 1] * R[i]);
cout<<Ans<<endl;
}
main()
{
#ifdef hk_cnyali
freopen("A.in", "r", stdin);
freopen("A.out", "w", stdout);
#endif
while (~scanf("%s", S + 1))
{
Init();
Solve();
memset(S, 0, sizeof S);
}
return 0;
}
|