POJ-3714 Raid 平面最近点对

　　题目链接：http://poj.org/problem?id=3714

　　分治算法修改该为两个点集的情况就可以了，加一个标记。。。

  1 //STATUS:C++_AC_2094MS_4880KB

  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 //#pragma comment(linker,"/STACK:102400000,102400000")

 25 //using namespace __gnu_cxx;

 26 //define

 27 #define pii pair<int,int>

 28 #define mem(a,b) memset(a,b,sizeof(a))

 29 #define lson l,mid,rt<<1

 30 #define rson mid+1,r,rt<<1|1

 31 #define PI acos(-1.0)

 32 //typedef

 33 typedef __int64 LL;

 34 typedef unsigned __int64 ULL;

 35 //const

 36 const int N=200010;

 37 const int INF=0x3f3f3f3f;

 38 const int MOD=10007,STA=8000010;

 39 const LL LNF=1LL<<55;

 40 const double EPS=1e-8;

 41 const double OO=1e30;

 42 const int dx[4]={-1,0,1,0};

 43 const int dy[4]={0,1,0,-1};

 44 const int day[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};

 45 //Daily Use ...

 46 inline int sign(double x){return (x>EPS)-(x<-EPS);}

 47 template<class T> T gcd(T a,T b){return b?gcd(b,a%b):a;}

 48 template<class T> T lcm(T a,T b){return a/gcd(a,b)*b;}

 49 template<class T> inline T lcm(T a,T b,T d){return a/d*b;}

 50 template<class T> inline T Min(T a,T b){return a<b?a:b;}

 51 template<class T> inline T Max(T a,T b){return a>b?a:b;}

 52 template<class T> inline T Min(T a,T b,T c){return min(min(a, b),c);}

 53 template<class T> inline T Max(T a,T b,T c){return max(max(a, b),c);}

 54 template<class T> inline T Min(T a,T b,T c,T d){return min(min(a, b),min(c,d));}

 55 template<class T> inline T Max(T a,T b,T c,T d){return max(max(a, b),max(c,d));}

 56 //End

 57 

 58 struct Node{

 59     double x,y;

 60     int id,index;

 61     Node(){}

 62     Node(double _x,double _y,int _index):x(_x),y(_y),index(_index){}

 63 }nod[N],temp[N];

 64 

 65 int n;

 66 

 67 double dist(Node &a,Node &b)

 68 {

 69     return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));

 70 }

 71 

 72 bool cmpxy(Node a,Node b)

 73 {

 74     return a.x!=b.x?a.x<b.x:a.y<b.y;

 75 }

 76 

 77 bool cmpy(Node a,Node b)

 78 {

 79     return a.y<b.y;

 80 }

 81 

 82 pii Closest_Pair(int l,int r)

 83 {

 84     if(l==r || l+1==r)return pii(l,r);

 85     double d,d1,d2;

 86     int i,j,k,mid=(l+r)/2;

 87     pii pn1=Closest_Pair(l,mid);

 88     pii pn2=Closest_Pair(mid+1,r);

 89     if(pn1.first==pn1.second || nod[pn1.first].index==nod[pn1.second].index)

 90         d1=OO;

 91     else d1=dist(nod[pn1.first],nod[pn1.second]);

 92     if(pn2.first==pn2.second || nod[pn2.first].index==nod[pn2.second].index)

 93         d2=OO;

 94     else d2=dist(nod[pn2.first],nod[pn2.second]);

 95 

 96     pii ret;

 97     d=Min(d1,d2);

 98     ret=d1<d2?pn1:pn2;

 99 

100     for(i=l,k=0;i<=r;i++){

101         if(fabs(nod[mid].x-nod[i].x)<=d){

102             temp[k++]=nod[i];

103         }

104     }

105     sort(temp,temp+k,cmpy);

106     for(i=0;i<k;i++){

107         for(j=i+1;j<k && fabs(temp[j].y-temp[i].y)<d;j++){

108             if(dist(temp[i],temp[j])<d && (temp[i].index^temp[j].index)){

109                 d=dist(temp[i],temp[j]);

110                 ret=make_pair(temp[i].id,temp[j].id);

111             }

112         }

113     }

114     return ret;

115 }

116 

117 void Init()

118 {

119     int i,t;

120     double x,y;

121     scanf("%d",&t);

122     n=t<<1;

123     for(i=0;i<t;i++){

124         scanf("%lf%lf",&x,&y);

125         nod[i]=Node(x,y,0);

126     }

127     for(;i<n;i++){

128         scanf("%lf%lf",&x,&y);

129         nod[i]=Node(x,y,1);

130     }

131     sort(nod,nod+n,cmpxy);

132     for(i=0;i<n;i++)nod[i].id=i;

133 }

134 

135 int main(){

136  //   freopen("in.txt","r",stdin);

137     int T,i,j;

138     scanf("%d",&T);

139     while(T--)

140     {

141         Init();

142         pii ans=Closest_Pair(0,n-1);

143 

144         printf("%.3lf\n",dist(nod[ans.first],nod[ans.second]));

145     }

146     return 0;

147 }