POJ-2296 Map Labeler 2sat

　　二分+2sat，每个点的上下两个方向为2sat的两个状态。
  1 //STATUS:C++_AC_16MS_536KB
  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=110;
 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 nod[N][2];
 58 int first[N*2],next[N*N*4],vis[N*2],S[N*2];
 59 int T,n,mt,cnt;
 60 
 61 struct Edge{
 62     int u,v;
 63 }e[N*N*4];
 64 
 65 void adde(int a,int b)
 66 {
 67     e[mt].u=a,e[mt].v=b;
 68     next[mt]=first[a];first[a]=mt++;
 69 }
 70 
 71 int dfs(int u)
 72 {
 73     if(vis[u^1])return 0;
 74     if(vis[u])return 1;
 75     int i;
 76     vis[u]=1;
 77     S[cnt++]=u;
 78     for(i=first[u];i!=-1;i=next[i]){
 79         if(!dfs(e[i].v))return 0;
 80     }
 81     return 1;
 82 }
 83 
 84 int Twosat()
 85 {
 86     int i,j;
 87     for(i=0;i<n;i+=2){
 88         if(vis[i] || vis[i^1])continue;
 89         cnt=0;
 90         if(!dfs(i)){
 91             while(cnt)vis[S[--cnt]]=0;
 92             if(!dfs(i^1))return 0;
 93         }
 94     }
 95     return 1;
 96 }
 97 
 98 int judge(double *a1,double *a2,double *b1,double *b2)
 99 {
100     if(Max(a1[0],a2[0])<=Min(b1[0],b2[0])
101        || Min(a1[0],a2[0])>=Max(b1[0],b2[0])
102        || Max(a1[1],a2[1])<=Min(b1[1],b2[1])
103        || Min(a1[1],a2[1])>=Max(b1[1],b2[1]))return 0;
104     return 1;
105 }
106 
107 void init(double limt)
108 {
109     int i,j,x,y;
110     double a1[2],a2[2],b1[2],b2[2];
111     mt=0;mem(vis,0);
112     mem(first,-1);
113     for(i=0;i<n;i++){
114         for(j=i+1;j<n;j++){
115             x=i<<1;y=j<<1;
116             a1[0]=nod[i][0]-limt/2,a1[1]=nod[i][1];b1[0]=nod[j][0]-limt/2,b1[1]=nod[j][1];
117             a2[0]=nod[i][0]+limt/2,b2[0]=nod[j][0]+limt/2;
118             a2[1]=nod[i][1]-limt;b2[1]=nod[j][1]-limt;
119             if(judge(a1,a2,b1,b2)){
120                 adde(x,y^1);adde(y,x^1);
121             }
122             b2[1]=nod[j][1]+limt;
123             if(judge(a1,a2,b1,b2)){
124                 adde(x,y);adde(y^1,x^1);
125             }
126             a2[1]=nod[i][1]+limt;b2[1]=nod[j][1]-limt;
127             if(judge(a1,a2,b1,b2)){
128                 adde(x^1,y^1);adde(y,x);
129             }
130             b2[1]=nod[j][1]+limt;
131             if(judge(a1,a2,b1,b2)){
132                 adde(x^1,y);adde(y^1,x);
133             }
134         }
135     }
136 }
137 
138 int binary(int l,int r)
139 {
140     int mid;
141     while(l<r){
142         mid=(l+r)>>1;
143      //   printf("%d %d
",l,r);
144         init(mid);
145         if(Twosat())l=mid+1;
146         else r=mid;
147     }
148     return l;
149 }
150 
151 int main()
152 {
153  //   freopen("in.txt","r",stdin);
154     int i,j;
155     scanf("%d",&T);
156     while(T--)
157     {
158         scanf("%d",&n);
159         for(i=0;i<n;i++){
160             scanf("%d%d",&nod[i][0],&nod[i][1]);
161         }
162 
163         printf("%d
",binary(0,20001)-1);
164     }
165     return 0;
166 }