[POJ3678] Katu Puzzle

題目

給出a,b,v三個整數和ope字符串
詢問是否存在一組{xi},xi={0,1} 滿足所有的xa ope xb=v
ope取值“AND”“OR”“XOR”

題解

經典的2-SAT問題
題解

代碼

/// by ztx
/// blog.csdn.net/hzoi_ztx
/// [poj] 3678: Katu Puzzle
/// submit with G++
#include <cstdio>
#define  Rep(i,l,r) for(i=(l);i<=(r);i++)
#define  Rev(i,r,l) for(i=(r);i>=(l);i--)
#define  maxe  4000100LL
#define  maxn  5000LL

struct FST { int to , next ; } e[maxe];
int star[maxn] = {0}, tote = 1;
inline void AddEdge(int u , int v) { e[++tote].to = v ; e[tote].next = star[u] ; star[u] = tote ; }

int DFN[maxn] = {0};
int LOW[maxn] = {0};
int sta[maxn] = {0}, top = 0;
bool insta[maxn] = {0};
int belong[maxn] = {0};
int idx = 0, cntblc = 0;

void dfs(int u) {
int v, p;
    DFN[u] = LOW[u] = ++idx;
    sta[++top] = u, insta[u] = true;
    for (p=star[u];p;p=e[p].next) {
        if (!DFN[v=e[p].to]) {
            dfs(v);
            if (LOW[u] > LOW[v]) LOW[u] = LOW[v];
        } else if (insta[v] && LOW[u]>DFN[v]) LOW[u] = DFN[v];
    }
    if (LOW[u] == DFN[u])
        for (cntblc++ ; u!=v ; ) {
            insta[v=sta[top]] = false;
            belong[v] = cntblc;
            top -- ;
        }
}


int n , m ;
int main() {
int i, a, b, w;
    scanf("%d%d", &n, &m) ;
    char ope[10];
    Rep (i,1,m) {
        scanf("%d%d%d%s", &a, &b, &w, ope);
        if (ope[0] == 'A') {
            if (w) {
                AddEdge(a+n,b+n);
                AddEdge(b+n,a+n);
                AddEdge(a,a+n);
                AddEdge(b,b+n);
            } else {
                AddEdge(a+n,b);
                AddEdge(b+n,a);
            }
        } else if (ope[0] == 'O') {
            if (w) {
                AddEdge(a,b+n);
                AddEdge(b,a+n);
            } else {
                AddEdge(a,b);
                AddEdge(b,a);
                AddEdge(a+n,a);
                AddEdge(b+n,b);
            }
        } else if (ope[0] == 'X') {
            if (w) {
                AddEdge(a,b+n);
                AddEdge(b,a+n);
                AddEdge(a+n,b);
                AddEdge(b+n,a);
            } else {
                AddEdge(a,b);
                AddEdge(b,a);
                AddEdge(a+n,b+n);
                AddEdge(b+n,a+n);
            }
        }
    }
    //Tarjan
    Rep (i,0,n*2-1)
        if (!DFN[i]) dfs(i);
    Rep (i,0,n-1)
        if (belong[i] == belong[i+n]){
            puts("NO");
            goto END;
        }
    puts("YES");
    END : getchar(), getchar();
    return 0 ;
}