2-sat模板

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技术分享
 1 #include<iostream>
 2 #include<algorithm>
 3 #include<cstdio>
 4 #include<cstring>
 5 #include<cmath>
 6 #include<cstdlib>
 7 #include<vector>
 8 using namespace std;
 9 typedef long long ll;
10 typedef long double ld;
11 typedef pair<int,int> pr;
12 const double pi=acos(-1);
13 #define rep(i,a,n) for(int i=a;i<=n;i++)
14 #define per(i,n,a) for(int i=n;i>=a;i--)
15 #define Rep(i,u) for(int i=head[u];i;i=Next[i])
16 #define clr(a) memset(a,0,sizeof(a))
17 #define pb push_back
18 #define mp make_pair
19 #define fi first
20 #define sc second
21 #define pq priority_queue
22 #define pqb priority_queue <int, vector<int>, less<int> >
23 #define pqs priority_queue <int, vector<int>, greater<int> >
24 #define vec vector
25 ld eps=1e-9;
26 ll pp=1000000007;
27 ll mo(ll a,ll pp){if(a>=0 && a<pp)return a;a%=pp;if(a<0)a+=pp;return a;}
28 ll powmod(ll a,ll b,ll pp){ll ans=1;for(;b;b>>=1,a=mo(a*a,pp))if(b&1)ans=mo(ans*a,pp);return ans;}
29 void fre() { freopen("c://test//input.in", "r", stdin); freopen("c://test//output.out", "w", stdout); }
30 //void add(int x,int y,int z){ v[++e]=y; next[e]=head[x]; head[x]=e; cost[e]=z; }
31 int dx[5]={0,-1,1,0,0},dy[5]={0,0,0,-1,1};
32 ll read(){ ll ans=0; char last= ,ch=getchar();
33 while(ch<0 || ch>9)last=ch,ch=getchar();
34 while(ch>=0 && ch<=9)ans=ans*10+ch-0,ch=getchar();
35 if(last==-)ans=-ans; return ans;
36 }
37 const int N=16005;
38 const int M=50000;
39 int head[N],Next[M],v[M],ans[N],S[N],top,e,n,m;
40 void add(int x,int y){ v[++e]=y; Next[e]=head[x]; head[x]=e;}
41 int dfs(int x){
42     if (ans[x]) return 1;
43     if (ans[x^1]) return 0;
44     ans[x]=1; S[++top]=x;
45     for (int i=head[x];i;i=Next[i]){
46         if (!dfs(v[i])) return 0; 
47     }
48     return 1;
49 }
50 int work(){
51     for (int i=0;i<n+n;i+=2){
52         if (ans[i] || ans[i^1]) continue;
53         top=0;
54         if (!dfs(i)){
55             while (top) ans[S[top--]]=0;
56             if (!dfs(i^1)) {
57                 while (top) ans[S[top--]]=0;
58                 return 0;
59             }
60         }
61     }
62     return 1;
63 }
64 int main(){
65     while (~scanf("%d%d",&n,&m)){
66         e=0;
67         for (int i=0;i<n+n;i++) head[i]=0;
68         while (m--){
69             int a=read(),b=read(); a--; b--;
70             add(a,b^1); add(b,a^1);
71         }
72         for (int i=0;i<n+n;i++) ans[i]=0;
73         if (!work()){
74             puts("NIE");
75         } else {
76             for (int i=0;i<n+n;i++)
77                 if (ans[i]) printf("%d\n",i+1);
78         }
79     }
80     return 0;
81 } 
View Code

2-sat:

技术分享
  1 #include<iostream>
  2 #include<algorithm>
  3 #include<cstdio>
  4 #include<cstring>
  5 #include<cmath>
  6 #include<cstdlib>
  7 #include<vector>
  8 using namespace std;
  9 typedef long long ll;
 10 typedef long double ld;
 11 typedef pair<int,int> pr;
 12 const double pi=acos(-1);
 13 #define rep(i,a,n) for(int i=a;i<=n;i++)
 14 #define per(i,n,a) for(int i=n;i>=a;i--)
 15 #define Rep(i,u) for(int i=head[u];i;i=Next[i])
 16 #define clr(a) memset(a,0,sizeof(a))
 17 #define pb push_back
 18 #define mp make_pair
 19 #define fi first
 20 #define sc second
 21 #define pq priority_queue
 22 #define pqb priority_queue <int, vector<int>, less<int> >
 23 #define pqs priority_queue <int, vector<int>, greater<int> >
 24 #define vec vector
 25 ld eps=1e-9;
 26 ll pp=1000000007;
 27 ll mo(ll a,ll pp){if(a>=0 && a<pp)return a;a%=pp;if(a<0)a+=pp;return a;}
 28 ll powmod(ll a,ll b,ll pp){ll ans=1;for(;b;b>>=1,a=mo(a*a,pp))if(b&1)ans=mo(ans*a,pp);return ans;}
 29 void fre() { freopen("c://test//input.in", "r", stdin); freopen("c://test//output.out", "w", stdout); }
 30 //void add(int x,int y,int z){ v[++e]=y; next[e]=head[x]; head[x]=e; cost[e]=z; }
 31 int dx[5]={0,-1,1,0,0},dy[5]={0,0,0,-1,1};
 32 ll read(){ ll ans=0; char last= ,ch=getchar();
 33 while(ch<0 || ch>9)last=ch,ch=getchar();
 34 while(ch>=0 && ch<=9)ans=ans*10+ch-0,ch=getchar();
 35 if(last==-)ans=-ans; return ans;
 36 }
 37 const int N=16005;
 38 const int M=50000;
 39 int head[N],Next[M],v[M],head_[N],Next_[M],v_[M],dfn[N],Time,Stack[N],Ins[N],low[N],ans[N],S[N],top,e,n,m,num,belong[N],in[N],l[N];
 40 #include<queue>
 41 queue<int> Q[2];
 42 void add(int x,int y){ v[++e]=y; Next[e]=head[x]; head[x]=e;}
 43 void add_(int x,int y){ v_[++e]=y; Next_[e]=head_[x]; head_[x]=e;}
 44 void Taj(int u){
 45     dfn[u]=low[u]=++Time; Stack[++top]=u; Ins[u]=1;
 46     for (int i=head[u];i;i=Next[i])
 47     if (dfn[v[i]]==0){
 48         Taj(v[i]);
 49         low[u]=min(low[u],low[v[i]]);
 50     } else if (Ins[v[i]]) low[u]=min(low[u],dfn[v[i]]);
 51     if (low[u]==dfn[u]){
 52         num++;
 53         while (Stack[top]!=u) {
 54             Ins[Stack[top]]=0;
 55             belong[Stack[top]]=num;
 56             top--;
 57         }
 58         Ins[Stack[top]]=0;
 59         belong[Stack[top]]=num;
 60         top--;
 61     }
 62 
 63 }
 64 int pd(){
 65         for (int i=0;i<n+n;i+=2){
 66                 if (belong[i+1]==belong[i]) return 1;
 67         }
 68         return 0;
 69 }
 70 void TopS(){
 71         for (int i=1;i<=num;i++)
 72         if (!in[i]){
 73                 Q[0].push(i);
 74         }
 75         int p=0;
 76         while (!Q[p%2].empty()){
 77                 while (!Q[p%2].empty()){
 78                         int u=Q[p%2].front(); Q[p%2].pop(); if (ans[l[u]]==1) continue; ans[u]=1;
 79                         for (int i=head_[u];i;i=Next_[i]){
 80                                 in[v_[i]]--;
 81                                 if (!in[v_[i]]) Q[(p+1)%2].push(v_[i]);
 82                         }
 83                 }
 84                 p++;
 85         }
 86         for (int i=0;i<n+n;i++)
 87         if (ans[belong[i]]){
 88                 printf("%d\n",i+1);
 89         }
 90 }
 91 int main(){
 92         while (~scanf("%d%d",&n,&m)){
 93                 e=0;
 94                 for (int i=0;i<n+n;i++) head[i]=0;
 95                 for (int i=0;i<n+n;i++) head_[i]=0;
 96                 while (m--){
 97                         int a=read(),b=read(); a--; b--;
 98                         add(a,b^1); add(b,a^1);
 99                 }
100                 top=0; num=0; Time=0; e=0;
101                 memset(dfn,0,sizeof(dfn));
102                 memset(low,0,sizeof(low));
103                 memset(Ins,0,sizeof(Ins));
104                 memset(ans,0,sizeof(ans));
105                 memset(in,0,sizeof(in));
106                 for (int i=0;i<n+n;i++)
107                 if (!dfn[i]) Taj(i);
108                 for (int i=0;i<n+n;i++){
109                         for (int j=head[i];j;j=Next[j]){
110                                 if (belong[i]!=belong[v[j]]){
111                                         add_(belong[v[j]],belong[i]); in[belong[i]]++;
112                                 }
113                         }
114                 }
115                 for (int i=0;i<n+n;i+=2){
116                         l[belong[i]]=belong[i+1];
117                         l[belong[i+1]]=belong[i];
118                 }
119                 if (pd()){
120                         puts("NIE\n");
121                 } else TopS();
122         }
123         return 0;
124 }
View Code

 

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