Codeforces 235C Cyclical Quest（后缀自动机）

代码

#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;
typedef long long ll;
const int maxn = 1e6 + 5;
const int SIGMA_SIZE = 26;

struct SAM {
int sz, last;
int g[maxn<<1][SIGMA_SIZE], pre[maxn<<1], step[maxn<<1];
int pos[maxn<<1], right[maxn<<1], cnt[maxn<<1], mark[maxn<<1];

void newNode(int s) {
step[++sz] = s;
pre[sz] = 0;
memset(g[sz], 0, sizeof(g[sz]));
}

int idx(char ch) { return ch -'a'; }

void init() {
sz = 0, last = 1;
newNode(0);
}

void insert(char ch);
void get_tuopu();
void get_right(char* str);

void presolve() {
for (int i = 1; i <= sz; i++) {
int u = pos[i];
printf("%d ", right[u]);
}
printf("\n");
}

int solve(char* str, int k, int mk) {
int ret = 0;
int p = 1, n = strlen(str), lcs = 0;

for (int i = 0; i < n; i++) {
int v = idx(str[i]);
if (g[p][v]) { lcs++, p = g[p][v]; }
else {
while (p && g[p][v] == 0) p = pre[p];

if (p) lcs = step[p] + 1, p = g[p][v];
else p = 1, lcs = 0;
}

if (lcs >= k) {
while (pre[p] && step[pre[p]] >= k) p = pre[p], lcs = step[p];
if (mark[p] != mk) {
mark[p] = mk;
ret += right[p];
}
}
}
return ret;
}
}SA;

char str[maxn], a[maxn];

int main () {
scanf("%s", str);
SA.init();

int n = strlen(str);
for (int i = 0; i < n; i++) SA.insert(str[i]);
SA.get_tuopu();
SA.get_right(str);

scanf("%d", &n);
for (int k = 1; k <= n; k++) {
scanf("%s", a);
int n = strlen(a), p = 0;
for (int i = 0; i < n; i++) str[p++] = a[i];
for (int i = 0; i < n-1; i++) str[p++] = a[i];
str[p++] = '\0';

printf("%d\n", SA.solve(str, n, k));
}
return 0;
}

void SAM::insert(char ch) {
newNode(step[last] + 1);
int v = idx(ch), p = last, np = sz;

while (p && !g[p][v]) {
g[p][v] = np;
p = pre[p];
}

if (p) {
int q = g[p][v];
if (step[q] == step[p] + 1)
pre[np] = q;
else {
newNode(step[p] + 1);
int nq = sz;
for (int j = 0; j < SIGMA_SIZE; j++) g[nq][j] = g[q][j];

pre[nq] = pre[q];
pre[np] = pre[q] = nq;

while (p && g[p][v] == q) {
g[p][v] = nq;
p = pre[p];
}
}
} else
pre[np] = 1;
last = np;
}

void SAM::get_tuopu() {
for (int i = 0; i <= sz; i++) cnt[i] = 0;
for (int i = 1; i <= sz; i++) cnt[step[i]]++;
for (int i = 1; i <= sz; i++) cnt[i] += cnt[i-1];
for (int i = 1; i <= sz; i++) pos[cnt[step[i]]--] = i;
}

void SAM::get_right(char* str) {
int p = 1, n = strlen(str);
for (int i = 0; i <= sz; i++) right[i] = 0;

for (int i = 0; i < n; i++) {
int v = idx(str[i]);
p = g[p][v];
right[p]++;
}

for (int i = sz; i; i--) {
int u = pos[i];
right[pre[u]] += right[u];
}
}