HU-814 Peaceful Comission 2 sat
17958 ワード
テーマリンク：http://acm.hdu.edu.cn/showproblem.php?pid=1814
簡単な2 sat問題です。
簡単な2 sat問題です。
1 //STATUS:C++_AC_390MS_996KB
2 #include <functional>
3 #include <algorithm>
4 #include <iostream>
5 //#include <ext/rope>
6 #include <fstream>
7 #include <sstream>
8 #include <iomanip>
9 #include <numeric>
10 #include <cstring>
11 #include <cassert>
12 #include <cstdio>
13 #include <string>
14 #include <vector>
15 #include <bitset>
16 #include <queue>
17 #include <stack>
18 #include <cmath>
19 #include <ctime>
20 #include <list>
21 #include <set>
22 #include <map>
23 using namespace std;
24 //using namespace __gnu_cxx;
25 //define
26 #define pii pair<int,int>
27 #define mem(a,b) memset(a,b,sizeof(a))
28 #define lson l,mid,rt<<1
29 #define rson mid+1,r,rt<<1|1
30 #define PI acos(-1.0)
31 //typedef
32 typedef long long LL;
33 typedef unsigned long long ULL;
34 //const
35 const int N=8010;
36 const int INF=0x3f3f3f3f;
37 const int MOD=5000,STA=100010;
38 const LL LNF=1LL<<60;
39 const double EPS=1e-8;
40 const double OO=1e15;
41 const int dx[4]={-1,0,1,0};
42 const int dy[4]={0,1,0,-1};
43 const int day[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
44 //Daily Use ...
45 inline int sign(double x){return (x>EPS)-(x<-EPS);}
46 template<class T> T gcd(T a,T b){return b?gcd(b,a%b):a;}
47 template<class T> T lcm(T a,T b){return a/gcd(a,b)*b;}
48 template<class T> inline T lcm(T a,T b,T d){return a/d*b;}
49 template<class T> inline T Min(T a,T b){return a<b?a:b;}
50 template<class T> inline T Max(T a,T b){return a>b?a:b;}
51 template<class T> inline T Min(T a,T b,T c){return min(min(a, b),c);}
52 template<class T> inline T Max(T a,T b,T c){return max(max(a, b),c);}
53 template<class T> inline T Min(T a,T b,T c,T d){return min(min(a, b),min(c,d));}
54 template<class T> inline T Max(T a,T b,T c,T d){return max(max(a, b),max(c,d));}
55 //End
56
57 int first[N*2],next[20000*2],vis[N*2],S[N*2];
58 int n,m,mt,cnt;
59
60 struct Edge{
61 int u,v;
62 }e[20000*2];
63
64 void adde(int a,int b)
65 {
66 e[mt].u=a,e[mt].v=b;
67 next[mt]=first[a];first[a]=mt++;
68 }
69
70 int dfs(int u)
71 {
72 if(vis[u^1])return 0;
73 if(vis[u])return 1;
74 int i;
75 vis[u]=1;
76 S[cnt++]=u;
77 for(i=first[u];i!=-1;i=next[i]){
78 if(!dfs(e[i].v))return 0;
79 }
80 return 1;
81 }
82
83 int Twosat()
84 {
85 int i,j;
86 for(i=0;i<n;i+=2){
87 if(vis[i] || vis[i^1])continue;
88 cnt=0;
89 if(!dfs(i)){
90 while(cnt)vis[S[--cnt]]=0;
91 if(!dfs(i^1))return 0;
92 }
93 }
94 return 1;
95 }
96
97 int main()
98 {
99 // freopen("in.txt","r",stdin);
100 int i,j,a,b;
101 while(~scanf("%d%d",&n,&m))
102 {
103 n<<=1;
104 mem(first,-1);mt=0;
105 mem(vis,0);
106 for(i=0;i<m;i++){
107 scanf("%d%d",&a,&b);
108 a--,b--;
109 adde(a,b^1);
110 adde(b,a^1);
111 }
112
113 if(Twosat()){
114 for(i=0;i<n;i+=2){
115 printf("%d
",(vis[i]?i:i^1)+1);
116 }
117 }
118 else puts("NIE");
119 }
120 return 0;
121 }