HDU 5020 Container Mark Slope

Test instructions: give you n points, let you find the maximum three points collinear, 1000 points

The puzzle: Obviously, the point 1000, the Normal enumeration O (N3), definitely not.

Method for map to record the slope of each point and other point lines, if the slope occurs more than 2, Num + = C (n,2);

Code:

#include <stdio.h> #include <iostream> #include <map>using namespaceStd;Map <double  ,  int> Mark; int Flag; struct Node {  int X,Y; }Cun[1005]; void Slove(Node A,Node b ) {  if  ( A.X ==B.X) {Flag ++ ; return  ;} Double K =(1.0 * (A.Y -B.Y)) / (1.0 * (A.X -B.X));Mark[K] ++; return  ; }int Slov (int A ) {  int K =A * (A-1) /2; return K; }  int  main() {  int T,N;scanf("%d",&T);  while (T--) {scanf("%d", &N);Mark.Clear();  for (int I =0;I<N;I++) {scanf("%d%d", &Cun[I].X, &Cun[I].Y); }  __int64 Num =0;Flag =0;  for (int I =0;I<N;I + +) {  for(int J =I+1;J<N;J++) {Slove (Cun[I],Cun[J]); }Map <double,  int;:: Iterator My_itr;  for (My_itr=Mark.Begin();My_itr!=Mark.End();++My_itr ) {  int K =My_itr -Second; if (K>=2)Num +=Slov(K); }  if( Flag>=2)Num +=Slov(Flag);Flag =0;Mark.Clear(); }Printf("%i64d\n",Num); } }

HDU 5020 Container Mark Slope