uva 1449 - Dominating Patterns(AC自动机)

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题目练级：uva 1449 - Dominating Patterns

题目大意：有一个由小写字母组成的字符串集和一个文本T，要求找出那些字符串在文本中出现的次数最多。

解题思路：将字符串集建立AC自动机，然后传入T进行匹配，对每个匹配上的字符串多应次数加1，最后找出最大值。出现次数与最大值相同的字符串输出。注意字符集中出现相同字符的情况。

#include <cstdio>#include <cstring>#include <queue>#include <string>#include <map>#include <algorithm>using namespace std;const int maxn = 155;const int maxl = 100;const int maxt = 1e6+5;const int sigma_size = 26;const int noden = maxn * maxl;char str[maxt], word[maxn][maxl];map<string, int> ms;int N, c[maxn];int sz, ac[noden][sigma_size], val[noden];int fail[noden], last[noden];void insert (int x, char* s) {    int u = 0, n = strlen(s);    for (int i = 0; i < n; i++) {        int v = s[i] - 'a';        if (ac[u][v] == 0) {            memset(ac[sz], 0, sizeof(ac[sz]));            val[sz] = 0;            ac[u][v] = sz++;        }        u = ac[u][v];    }    val[u] = x;}void get_fail () {    queue<int> que;    fail[0] = 0;    for (int i = 0; i < sigma_size; i++) {        int u = ac[0][i];        if (u) {            fail[u] = last[u] = 0;            que.push(u);        }    }    while (!que.empty()) {        int r = que.front();        que.pop();        for (int i = 0; i < sigma_size; i++) {            int u = ac[r][i];            if (u == 0) {                ac[r][i] = ac[fail[r]][i];                continue;            }            que.push(u);            int v = fail[r];            while (v && !ac[v][i])                v = fail[v];            fail[u] = ac[v][i];            last[u] = val[fail[u]] ? fail[u] : last[fail[u]];        }    }}void count (int x) {    if (x) {        c[val[x]]++;        count(last[x]);    }}void find (char* T) {    int u = 0;    int n = strlen(T);    for (int i = 0; i < n; i++) {        int v = T[i] - 'a';        /*        while (u && !ac[u][v])            u = fail[u];            */        u = ac[u][v];        if (val[u])            count(u);        else            count(last[u]);    }}void init () {    sz = 1;    ms.clear();    memset(ac[0], 0, sizeof(ac[0]));    for (int i = 1; i <= N; i++) {        scanf("%s", word[i]);        insert(i, word[i]);        ms[string(word[i])] = i;    }    memset(c, 0, sizeof(c));    get_fail();}int main () {    while (scanf("%d", &N) == 1 && N) {        init();        scanf("%s", str);        find(str);        int ans = -1;        for (int i = 1; i <= N; i++)            ans = max(ans, c[i]);        printf("%d\n", ans);        for (int i = 1; i <= N; i++) {            if (c[ms[string(word[i])]] == ans)                printf("%s\n", word[i]);        }    }    return 0;}

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