【HDOJ】2828 Lamp

DLX简单题目。

/*  */
#include <iostream>
#include <sstream>
#include <string>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#include <deque>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <climits>
#include <cctype>
#include <cassert>
#include <functional>
#include <iterator>
#include <iomanip>
using namespace std;
//#pragma comment(linker,"/STACK:102400000,1024000")

#define sti                set<int>
#define stpii            set<pair<int, int> >
#define mpii            map<int,int>
#define vi                vector<int>
#define pii                pair<int,int>
#define vpii            vector<pair<int,int> >
#define rep(i, a, n)     for (int i=a;i<n;++i)
#define per(i, a, n)     for (int i=n-1;i>=a;--i)
#define clr                clear
#define pb                 push_back
#define mp                 make_pair
#define fir                first
#define sec                second
#define all(x)             (x).begin(),(x).end()
#define SZ(x)             ((int)(x).size())
#define lson            l, mid, rt<<1
#define rson            mid+1, r, rt<<1|1

const int INF = 0x3f3f3f3f;

typedef struct {
    static const int maxn = 1e6+5;
    
    int L[maxn], R[maxn], U[maxn], D[maxn];
    int H[maxn];
    int row[maxn], col[maxn], S[maxn];
    
    bool visit[1205];
    int sz;
    int ans[maxn], ansd;
    
    void init(int n) {
        rep(i, 0, n+1) {
            L[i] = i - 1;
            R[i] = i + 1;
            U[i] = i;
            D[i] = i;
            col[i] = i;
        }
        
        memset(S, 0, sizeof(S));
        memset(visit, false, sizeof(visit));
        memset(H, -1, sizeof(H));
        R[n] = 0;
        L[0] = n;
        sz = n + 1;
    }
    
    void link(int r, int c) {
        U[sz] = c;
        D[sz] = D[c];
        U[D[c]] = sz;
        D[c] = sz;
        if (H[r] < 0) {
            H[r] = L[sz] = R[sz] = sz;
        } else {
            L[sz] = H[r];
            R[sz] = R[H[r]];
            L[R[H[r]]] = sz;
            R[H[r]] = sz;
        }
        
        ++S[c];
        col[sz] = c;
        row[sz] = r;
        ++sz;
    }
    
    void remove(int c)  {
        L[R[c]] = L[c];
        R[L[c]] = R[c];
        for (int i=D[c]; i!=c; i=D[i]) {
            for (int j=R[i]; j!=i; j=R[j]) {
                U[D[j]] = U[j];
                D[U[j]] = D[j];
                --S[col[j]];
            }
        }
    }
    
    void restore(int c)  {
        L[R[c]] = c;
        R[L[c]] = c;
        for (int i=D[c]; i!=c; i=D[i]) {
            for (int j=R[i]; j!=i; j=R[j]) {
                U[D[j]] = j;
                D[U[j]] = j;
                ++S[col[j]];
            }
        }
    }
    
    void remove_(int c) {
        for (int i=D[c]; i!=c; i=D[i]) {
            L[R[i]] = L[i];
            R[L[i]] = R[i];
        }
    }
    
    void restore_(int c) {
        for (int i=D[c]; i!=c; i=D[i]) {
            L[R[i]] = i;
            R[L[i]] = i;
        }
    }
    
    bool dfs(int cur) {
        if (!R[0]) {
            return true;
        }
        
        int c = R[0];
        for (int i=R[0]; i!=0; i=R[i]) {
            if (S[i] < S[c])
                c = i;
        }
        
        for (int i=D[c]; i!=c; i=D[i]) {
            if (visit[row[i]^1])
                continue;
            visit[row[i]] = true;
            remove_(i);
            for (int j=R[i]; j!=i; j=R[j])
                remove_(j);
            if (dfs(cur+1))    return true;
            for (int j=L[i]; j!=i; j=L[j])
                restore_(j);
            restore_(i);
            visit[row[i]] = false;
        }
        
        return false;
    }
    
} DLX;

DLX solver;

int main() {
    ios::sync_with_stdio(false);
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
        freopen("data.out", "w", stdout);
    #endif
    
    int n, m;
    int ln, k;
    char op[8];
    bool flag;
    
    while (scanf("%d %d", &n, &m)!=EOF) {
        solver.init(n);
        rep(i, 1, n+1) {
            scanf("%d", &ln);
            while (ln--) {
                scanf("%d %s", &k, op);
                --k;
                if (op[1] == 'N') {
                    solver.link(k<<1, i);
                } else {
                    solver.link(k<<1|1, i);
                }
            }
        }
        
        flag = solver.dfs(0);
        if (flag) {
            if (solver.visit[1]) {
                printf("OFF");
            } else {
                printf("ON");
            }
            m <<= 1;
            for (int i=2; i<m; i+=2) {
                if (solver.visit[i]) {
                    printf(" ON");
                } else {
                    printf(" OFF");
                }
            }
            putchar('
');
        } else {
            puts("-1");
        }
    }
    
    #ifndef ONLINE_JUDGE
        printf("time = %d.
", (int)clock());
    #endif
    
    return 0;
}