hdu 4622 Reincarnation（SAM）

解题思路

代码

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

using namespace std;
typedef long long ll;
const int maxn = 4005;
const int SIGMA_SIZE = 26;

struct SAM {
int sz, last;
int g[maxn<<1][SIGMA_SIZE], pre[maxn<<1], step[maxn<<1];
int tot;

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

int 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;
tot += step[np] - step[pre[np]];
last = np;
return tot;
}
}SA;

char str[maxn];
int ans[maxn][maxn];

int main () {
int cas;
scanf("%d", &cas);
while (cas--) {
scanf("%s", str);
int n = strlen(str), u, v;
for (int i = 0; i < n; i++) {
SA.init();
for (int j = i; j < n; j++)
ans[i+1][j+1] = SA.insert(str[j]);
}

scanf("%d", &n);
while (n--) {
scanf("%d%d", &u, &v);
printf("%d\n", ans[u][v]);
}
}
return 0;
}