HDU2471 2008 Asia Regional Hangzhou History of Languages

给出两个DFA的状态转换表，判断两个DFA是否相同。

需要先处理循环路径，即通过某路径后无法达到AC状态，但可能通过该路径后两个DFA的状态转换不相同，这种情况下两个DFA依然是相同的，所以要把这样的路径封死。

从AC状态反向建图，BFS封死上述路径，再从0状态BFS同步对比两DFA状态转换。

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<queue>
using namespace std;
const int maxn = 2011;
const int maxm = 27;

bool vis[maxn][maxn], ac1[maxn], ac2[maxn];
int f1[maxn][maxm], f2[maxn][maxm];
int t, n1, n2;
struct qu
{
    int s1, s2;
    qu()
    {
        s1 = s2 = 0;
    }
    qu(int a, int b)
    {
        s1 = a, s2 = b;
    }
};
queue<qu> q;
bool BFS()
{
    qu lin;
    memset(vis, 0, sizeof(vis));
    while(!q.empty()) q.pop();
    q.push(qu()), vis[0][0] = true;
    while(!q.empty())
    {
        lin = q.front(), q.pop();
        if(lin.s1 >= n1 || lin.s2 >= n2) return false;
        if(ac1[lin.s1] != ac2[lin.s2]) return false;
        for(int i = 0; i < t; ++ i)
        {
            if(!!(f1[lin.s1][i] + 1) != !!(f2[lin.s2][i] + 1)) return false;
            if(f1[lin.s1][i] == -1)continue;
            if(!vis[f1[lin.s1][i]][f2[lin.s2][i]])
            {
                vis[f1[lin.s1][i]][f2[lin.s2][i]] = true;
                q.push(qu(f1[lin.s1][i], f2[lin.s2][i]));
            }
        }
    }
    return true;
}
int fst[maxn], nex[maxn *maxn], v[maxn *maxn], wnum;
bool ok[maxn];
void BFSCUT(bool *ac, int n)
{
    queue<int> q;
    int i;
    memset(ok, 0, sizeof(ok));
    for(i = 0; i < n; ++ i) if(ac[i]) q.push(i), ok[i] = true;
    while(!q.empty())
    {
        for(i = fst[q.front()], q.pop(); i != -1; i = nex[i])
            if(!ok[v[i]]) ok[v[i]] = true, q.push(v[i]);
    }
}
void ReadData(bool *ac, int f[][maxm], int *n)
{
    scanf("%d", n);
    memset(fst, -1, sizeof(fst));
    wnum = 0;
    for(int i = 0, x; i < *n; ++ i)
    {
        scanf("%d", &x), ac[i] = x;
        for(int j = 0; j < t; ++ j)
        {
            scanf("%d", &f[i][j]);
            if(f[i][j] != -1)
            {
                nex[wnum] = fst[f[i][j]];
                fst[f[i][j]] = wnum;
                v[wnum] = i;
                ++ wnum;
            }
        }
    }
    BFSCUT(ac, *n);
    for(int i = 0; i < *n; ++ i)
        for(int j = 0; j < t; ++ j)
            if(f[i][j] != -1 && !ok[f[i][j]]) f[i][j] = -1;
}
int main()
{
    int ca = 0;
    while(scanf("%d", &t), t)
    {
        ReadData(ac1, f1, &n1);
        ReadData(ac2, f2, &n2);
        printf("Case #%d: ", ++ ca);
        printf(BFS() ? "Yes\n" : "No\n");
    }
    return 0;
}