hdu 3407 DFA

上次在北大暑期课期末考试里遇到这道题。最开始我是用BF实现DFA，超时。后来参考别人的程序用Trie实现，过了，但是还是理解得不够透彻。这几天做了不少KMP的题目，今天就用KMP实现了这个DFA，过了，很有成就感，呵呵~~

/*
 * hdu3407/linux.cpp
 * Created on: 2011-7-29
 * Author    : ben
 */
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;

#define MAX_LEN 10005
char pattern[MAX_LEN];
int state[MAX_LEN][26];
int len;
int nextval[MAX_LEN];

void get_next() {
    int i = 0, j = -1;
    int parlen = len;
    nextval[0] = -1;
    while (i <= parlen) {
        if (j == -1 || pattern[i] == pattern[j]) {
            i++;
            j++;
            nextval[i] = j;
        } else {
            j = nextval[j];
        }
    }
}

void work() {
    int i, j, cur;
    char c;
    while (scanf("%s", pattern) != EOF) {
        if (strcmp(pattern, "0") == 0) {
            break;
        }
        len = strlen(pattern);
        get_next();
        memset(state, 0, sizeof(state));
        for (cur = 0; cur <= len; cur++) {
            for (c = 'a'; c <= 'z'; c++) {
                i = cur;
                while(i >= 0 && c != pattern[i]) {
                    i = nextval[i];
                }
                state[cur][c - 'a'] = i + 1;
            }
        }
        for (i = 0; i <= len; i++) {
            printf("%d", i);
            for (j = 0; j < 26; j++) {
                printf(" %d", state[i][j]);
            }
            printf("\n");
        }
    }
}

int main() {
#ifndef ONLINE_JUDGE
    freopen("data.in", "r", stdin);
#endif
    work();
    return 0;
}