最近点对算法最近点对问题

最近点对算法:最近点对问题
疯狂代码 http://www.crazycoder.cn/ ĵ:http:/www.crazycoder.cn/VC/Article66512.html
通过代码来学习例子看下面代码: //点结构 typedef struct Pair { x; y; } Pair ; //最近点对结构 typedef struct Closest_Pair { Pair pair_a ,pair_b ; double distance ; } Closest_Pair ; //点对结构 typedef struct Pos { Pair* p_pair ;
}
} } //--------------------------------------------------------------------------void MSort(char sign ,Pair SR ,Pair TR1 ,long s , long t) { // 将SR[s..t]归并排序为TR1[s..t].
double distance ; } Closest_Pair ; typedef struct Pos { Pair* p_pair ; pair_nums ;//点对数目 } Pos ; //---------------------------------------------------------------------------
void Comp_CP(const Pos& pos ,Closest_Pair& closest_pair , mid , mid_value) { i,j; distance = sqrt( closest_pair.distance ) ; i = mid ; while( i >= 0 && pos.p_pair[i].x > (mid_value-distance) ) { j = mid ;
( (A.x-B.x)*(A.x-B.x)+(A.y-B.y)*(A.y-B.y) ) ; }
//--------------------------------------------------------------------------void Pr_Pos(ostream& outs ,const Pos& pos ,const Closest_Pair& closest_pair ) { outs << "\n\n\n 随机产生点对如下:\n" ; for( i=0 ;i<pos.pair_nums ;i) { outs << " (" << pos.p_pair[i].x << " , " << pos.p_pair[i].y << " ) " ; ((i+1)%50) { outs << endl ; } } outs << "\n\n 由以上点对可得最近点对为: ( " << closest_pair.pair_a.x << " , " << closest_pair.pair_a.y << " ) ,( " << closest_pair.pair_b.x << " , " << closest_pair.pair_b.y << " ) " ; outs << "\n 该点对距离为:" << closest_pair.distance << endl ; } //---------------------------------------------------------------------------
;Βιβλιοθήκη Baidu}
# "Head.h" //--------------------------------------------------------------------------typedef RedType ; typedef struct Pair { x; y; } Pair ; typedef struct Closest_Pair { Pair pair_a ,pair_b ;
TR[k]=SR[j]; }
{ ( SR[i].y < SR[j].y ) TR[k]=SR[i];
TR[k]=SR[j]; } } (i<=m) { for( l=0;l<=m-i;l) { TR[k+l]=SR[i+l]; // 将剩余SR[i..m]复制到TR } }
{ for( l=0;l<=n-j;l) { TR[k+l]=SR[j+l]; // 将剩余SR[j..n]复制到TR
Merge(sign ,TR2,TR1,s,m,t) ; // 将TR2[s..m]和TR2[m+1..t]归并到TR1[s..t]
delete TR2 ; }
// cout << " Hello " ;
} //---------------------------------------------------------------------------
} i-- ; }
} //--------------------------------------------------------------------------void Divide_and_Conquer(const Pos& pos ,Closest_Pair& closest_pair , from , to) { ( (to-from+1) <4 ) { Brute_Force(pos ,closest_pair ,from ,to ) ; cout << "<4 " << closest_pair.distance << endl ; //system("pause") ; }
{ mid = (from+to)/2 ; mid_value = pos.p_pair[mid].x ;
Divide_and_Conquer(pos ,closest_pair ,from ,mid) ; Divide_and_Conquer(pos ,closest_pair ,mid+1 ,to) ; Comp_CP(pos ,closest_pair ,mid ,mid_value) ;
bool Brute_Force(const Pos& pos ,Closest_Pair& closest_pair , from , to) { for( i=from ;i<=to ;i) { for( j=i+1;j<=to ;j) { double next = Account_Distance_2(pos.p_pair[i] ,pos.p_pair[j]) ;//sqrt( ) (closest_pair.distance > next ) { closest_pair.pair_a = pos.p_pair[i] ; closest_pair.pair_b = pos.p_pair[j] ; closest_pair.distance = next ; } } }
(st) { TR1[s] = SR[s]; }
{ // m ; length = t-s+1 ;// Pair* TR2 = Pair[pos.pair_nums]; long m = (s+t)/2; // 将SR[s..t]平分为SR[s..m]和SR[m+1..t] MSort(sign ,SR,TR2,s,m) ; // 递归地将SR[s..m]归并为有序TR2[s..m] MSort(sign ,SR,TR2,m+1,t) ; // 递归地将SR[m+1..t]归并为有序TR2[m+1..t]
true ; }
//-------------------------------------------------------------------------// 对顺序表L作归并排序 void Merge(char sign ,Pair SR ,Pair TR ,long i ,long m ,long n) { // 将有序SR[i..m]和SR[m+1..n]归并为有序TR[i..n] // j,k,l; for( j=m+1,k=i;i<=m&&j<=n;k) // 将SR中记录由小到大地并入TR { (sign'x') { ( SR[i].x < SR[j].x ) TR[k]=SR[i];
true ; } //分治法:遵循分治思路方法利用递归求出左子集和右子集最近点对然后再对两子集的间点对进步分析比较最后 求出整个点集最近点对 void Divide_and_Conquer(const Pos& pos ,Closest_Pair& closest_pair , from , to) { ( (to-from+1) <4 ) { Brute_Force(pos ,closest_pair ,from ,to ) ; cout << "<4 " << closest_pair.distance << endl ; //system("pause") ; }
Pos pos ; Closest_Pair closest_pair ; // pair_nums ; //--------------------------------------------------------------------------double Account_Distance_2(const Pair& A ,const Pair& B ) {
{ mid = (from+to)/2 ; mid_value = pos.p_pair[mid].x ;
Divide_and_Conquer(pos ,closest_pair ,from ,mid) ;
Divide_and_Conquer(pos ,closest_pair ,mid+1 ,to) ; Comp_CP(pos ,closest_pair ,mid ,mid_value) ; }
while( pos.p_pair[j].x < (mid_value+distance) && j < pos.pair_nums ) { ( pos.p_pair[j].y > (pos.p_pair[i].y+distance) || pos.p_pair[j].y < (pos.p_pair[i].y-distance) ) //判断在y轴是否出界 continue ; double next = Account_Distance_2( pos.p_pair[i] ,pos.p_pair[j]);//sqrt( ) (closest_pair.distance > next ) { closest_pair.pair_a = pos.p_pair[i] ; closest_pair.pair_b = pos.p_pair[j] ; closest_pair.distance = next ; cout << "Comp_CP: " << closest_pair.distance << endl ; }
pair_nums ;//点对数目 } Pos
//蛮力法:分别计算每对点的间距离然后找距离最小那对 bool Brute_Force(const Pos& pos ,Closest_Pair& closest_pair , from , to) { for( i=from ;i<=to ;i) { for( j=i+1;j<=to ;j) { double next= Account_Distance_2(pos.p_pair[i] ,pos.p_pair[j]) ; (closest_pair.distance > next ) { closest_pair.pair_a = pos.p_pair[i] ; closest_pair.pair_b = pos.p_pair[j] ; closest_pair.distance = next ; } } }