poj 3648(2-SAT)

poj 3648
1、注意2-SAT的定义(例如此题定义坐不坐新郎这边比坐不坐新娘这边更好解题)
2、取了和题目不同定义时，记得反一下

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;
#define ms(i,j) memset(i, j, sizeof i);

const int MAXN = 200 + 5;

struct TwoSAT
{
    vector<int> G[MAXN*2];
    int S[MAXN*2];
    bool mark[MAXN*2];
    int n, c;
    void init(int n)
    {
        this->n = n;
        for (int i=0;i<=2*n;i++)
        {
            G[i].clear();
            mark[i] = false;
        }
    }
    void ins(int u, int v)
    {
        G[u].push_back(v);
    }
    int dfs(int x)
    {
        if (mark[x^1]) return false;
        if (mark[x]) return true;
        mark[x] = true;
        S[++c] = x;
        for (int i=0;i<G[x].size();i++) 
        {
            if (!dfs(G[x][i])) return false;
        }
        return true;
    }
    int solve()
    {
        for (int i=0;i<2*n;i+=2)
        if (!mark[i]&&!mark[i+1]) 
        {
            c = 0;
            if (!dfs(i))
            {
                while (c>0) mark[S[c--]] = false;
                if (!dfs(i+1)) return false;
            }
        }
        return true;
    }
}ts;

int n, m;

void init()//2*x is h, 2*x+1 is w
{
    ts.init(n);
    ts.ins(1, 0);//the groom must be in the line
    for (int i=1;i<=m;i++)
    {
        int a,b;
        char as, bs;
        scanf("%d%c%d%c", &a, &as, &b, &bs);
        if (as=='h'&&bs=='w')
        {
            ts.ins(2*a, 2*b);//ha->hb
            ts.ins(2*b+1, 2*a+1);//wb->wa
        }
        if (as=='w'&&bs=='h')
        {
            ts.ins(2*b, 2*a);//hb->ha
            ts.ins(2*a+1, 2*b+1);//wa->wb
        }
        if (as=='h'&&bs=='h')
        {
            ts.ins(2*a, 2*b+1);//ha->wb
            ts.ins(2*b, 2*a+1);//hb->wa
        }
        if (as=='w'&&bs=='w')
        {
            ts.ins(2*a+1, 2*b);//wa->hb
            ts.ins(2*b+1, 2*a);//wb->ha
        }
    }
}
void solve()
{
    bool flag = false;
    if (ts.solve())
    {
        for (int i=1;i<ts.n;i++)
        {
            if (ts.mark[i*2]) 
            {
                if (flag) printf(" ");
                printf("%dw", i), flag = true;
            }
            if (ts.mark[i*2+1]) 
            {
                if (flag) printf(" ");
                printf("%dh", i), flag = true;
            }
        }
        printf("\n");
    } else printf("bad luck\n");
}
int main()
{
    while (scanf("%d%d", &n, &m)==2&&n&&m)
    {
        init();
        solve();
    }
    return 0;
}