版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/Game_Acm/article/details/82429445
int tol,head[maxn];
struct edge
{
int to,next;
}es[maxm];
void addedge( int u , int v )
{
es[tol].to = v;
es[tol].next = head[u];
head[u] = tol++;
}
bool vis[maxn]; int S[maxn],top;
bool dfs( int u )
{
if ( vis[u^1] ) return false;
if ( vis[u] ) return true;
vis[u] = true;
S[top++] = u;
for ( int i=head[u] ; i!=-1 ; i=es[i].next )
if ( !dfs(es[i].to) ) return false;
return true;
}
bool Twosat( int n )
{
memset ( vis , false , sizeof(vis) );
for ( int i=0 ; i<n ; i+=2 )
{
if ( vis[i]||vis[i^1] ) continue;
top = 0;
if ( !dfs(i) )
{
while ( top ) vis[S[--top]] = false;
if ( !dfs(i^1) ) return false;
}
}
return true;
}