POJ 3678 Katu Puzzle 2-SAT

和上一篇差不多，代码稍多
迷一样的数据，边数只开3W都能A？

#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>using namespace std;#define ms(i) memset(i,0,sizeof(i))const int N = 2005, M = 30000;struct TwoSAT {    int h[N], p[M], v[M], vis[N], stk[N], top, cnt, n;    void add(int a, int x, int b, int y) {        a = 2 * a + x; b = 2 * b + y;        p[++cnt] = h[a ^ 1]; v[cnt] = b; h[a ^ 1] = cnt;        p[++cnt] = h[b ^ 1]; v[cnt] = a; h[b ^ 1] = cnt;    }    void init(int a) {        cnt = 0; n = a; ms(vis); ms(h);    }    bool solve() {        for(int i=0;i<2*n;i+=2) if (!vis[i]&&!vis[i^1]) {            top = 0;            if (!dfs(i)) {                while (top) vis[stk[--top]] = 0;                if (!dfs(i + 1)) return 0;            }        }        return 1;    }    bool dfs(int x) {        if (vis[x ^ 1]) return 0;        if (vis[x]) return 1;        vis[x] = 1; stk[top++] = x;        for (int i = h[x]; i; i = p[i])            if (!dfs(v[i])) return 0;        return 1;    }} g;int main() {    int n, m, a, b, c;    char d[4];    while (scanf("%d%d", &n, &m) == 2) {        g.init(n);        while (m--) {            scanf("%d%d%d%s", &a, &b, &c, d);            if (d[0] == 'A')                if (c) {                    g.add(a, 0, b, 0);                    g.add(a, 0, b, 1);                    g.add(a, 1, b, 0);                } else                     g.add(a, 1, b, 1);            else if (d[0] == 'O')                if (c)                    g.add(a, 0, b, 0);                else {                    g.add(a, 0, b, 1);                    g.add(a, 1, b, 1);                    g.add(a, 1, b, 1);                }            else if (d[0] == 'X')                if (c) {                    g.add(a, 0, b, 0);                    g.add(a, 1, b, 1);                } else {                    g.add(a, 0, b, 1);                    g.add(a, 1, b, 0);                }        }        puts(g.solve() ? "YES" : "NO");    }    return 0;}

Katu Puzzle

Time Limit: 1000MS Memory Limit: 65536K
Total Submissions: 9028 Accepted: 3346

Description

Katu Puzzle is presented as a directed graph G(V, E) with each edge e(a, b) labeled by a boolean operator op (one of AND, OR, XOR) and an integer c (0 ≤ c ≤ 1). One Katu is solvable if one can find each vertex Vi a value Xi (0 ≤ Xi ≤ 1) such that for each edge e(a, b) labeled by op and c, the following formula holds:

Xa op Xb = c

The calculating rules are:

AND 0 1
0 0 0
1 0 1
OR 0 1
0 0 1
1 1 1
XOR 0 1
0 0 1
1 1 0
Given a Katu Puzzle, your task is to determine whether it is solvable.

Input

The first line contains two integers N (1 ≤ N ≤ 1000) and M,(0 ≤ M ≤ 1,000,000) indicating the number of vertices and edges.
The following M lines contain three integers a (0 ≤ a < N), b(0 ≤ b < N), c and an operator op each, describing the edges.

Output

Output a line containing “YES” or “NO”.

Sample Input

4 4
0 1 1 AND
1 2 1 OR
3 2 0 AND
3 0 0 XOR

Sample Output

YES
Hint

X0 = 1, X1 = 1, X2 = 0, X3 = 1.