poj 2318 TOYS 2012-01-11

http://poj.org/problem?id=2318

___________________________________________________

题目大意：一个箱子用木板分成几个区间，给一些玩具的坐标，求各个区间有几个玩具。

  对于每一个玩具，因为输入的区间是有序的，所以采用二分木板，判断一个玩具在哪个区间。

 

___________________________________________________

Program Stone;
var i,n,m,x1,x2,y1,y2,xi,yi:longint;
    ui,li:array[0..10000]of longint;
    ans:array[0..10000]of longint;
 procedure init;
 var i,j,k:longint;
  begin
     readln(n,m,x1,y1,x2,y2);
     ui[0]:=x1;li[0]:=x1;
     ui[n+1]:=x2;li[n+1]:=x2;
     if n=0 then halt;
     for i:=1 to n do readln(ui[i],li[i]);
  end;
 Function cross(x1,y1,x2,y2,x3,y3,x4,y4:longint):longint;    //叉积
  begin
    cross:=(x2-x1)*(y4-y3)-(y2-y1)*(x4-x3);
  end;
 function ef(x,y:longint):longint;
 var i,j,k,left,right,mid:longint;
  begin
     left:=0;right:=n+1;
     while left+1<right do
      begin
         mid:=(left+right)div 2;
         k:=cross(li[mid],y2,ui[mid],y1,li[mid],y2,x,y);
         if k<0 then left:=mid;
         if k>0 then right:=mid;
      end;
     ef:=left;
  end;
 Procedure print;
 var i:longint;
  begin
    for i:=0 to n do
     writeln(i,': ',ans[i]);
    writeln;
    fillchar(ans,sizeof(ans),0);
  end;
Begin
 assign(input,'input.in');reset(input);
   while true do
    begin
       init;
       for i:=1 to m do
        begin
          readln(xi,yi);
          inc(ans[ef(xi,yi)]);
        end;
       print;
    end;
end.