POJ 2540 Hotter Colder

http://poj.org/problem?id=2540

Test instructions: give you the path of each walk, and tell you each time away from a point light source is far or near, requiring each light source may exist in the area of the location.

Idea: If the "Same", indicating the light source on the perpendicular bisector, the area is 0, otherwise we consider far or near, in fact, in the path of two points connected to a straight line of the perpendicular bisector is a half-plane line, near the far side of the line, far away in the line near the side.

1#include <cstdio>2#include <iostream>3#include <cmath>4#include <cstring>5#include <algorithm>6 Const DoublePi=acos (-1);7 BOOLflag=0;8 inttot;9 structpoint{Ten     Doublex, y; One Point () {} APoint (DoubleX0,Doubley0): X (x0), Y (y0) {} -}a[200005],p[200005]; - structline{ the Point s,e; -     Doubleslop; - Line () {} - Line (Point S0,point E0): S (s0), E (E0) {} +}l[200005],l[200005],c[200005]; - intRead () { +     intt=0, f=1;CharCh=GetChar (); A      while(ch<'0'|| Ch>'9'){if(ch=='-') f=-1; ch=GetChar ();} at      while('0'<=ch&&ch<='9') {t=t*Ten+ch-'0'; ch=GetChar ();} -     returnt*F; - } - Double operator*(Point p1,point p2) { -     returnp1.x*p2.y-p1.y*p2.x; - } inPointoperator+(Point p1,point p2) { -     returnPoint (p1.x+p2.x,p1.y+p2.y); to } +Pointoperator-(Point p1,point p2) { -     returnPoint (p1.x-p2.x,p1.y-p2.y); the } *Pointoperator/(Point P1,Doublex) { $     returnPoint (p1.x/x,p1.y/x);Panax Notoginseng } - BOOLCMP (line p1,line p2) { the     if(P1.slop!=p2.slop)returnp1.slop<P2.slop; +     Else return(P1.E-P1.S) * (P2.E-P1.S) <=0; A } thePoint Turn (Point P1,Doubleang) { +     DoubleCos=cos (ANG), sin=sin (ang); -     Doublex=p1.x*cos-p1.y*Sin; $     Doubley=p1.x*sin+p1.y*Cos; $     returnPoint (x, y); - } - Point Inter (line p1,line p2) { the     Doublet1= (P2.E-P1.S) * (p1.e-p1.s); -     DoubleT2= (P1.E-P1.S) * (p2.s-p1.s);Wuyi     Doublek= (T2)/(t1+T2); the     Doublex= (p2.e.x-p2.s.x) *k+p2.s.x; -     DoubleY= (P2.E.Y-P2.S.Y) *k+P2.s.y; Wu     returnPoint (x, y); - } About BOOLJud (line p1,line p2,line p3) { $Point p=Inter (P1,P2); -     return(P-P3.S) * (P3.E-P3.S) >0; - } - Doublequery () { AStd::sort (L +1, L +1+tot,cmp); +     if(!CMP (l[tot-1],l[tot]))return 0.0; the     intCnt=1; l[1]=l[1]; -      for(intI=2; i<=tot;i++) $      if(l[i].slop!=l[i-1].slop) l[++cnt]=L[i]; the     intLl=1, rr=2; c[ll]=l[1];c[rr]=l[2]; the      for(intI=3; i<=cnt;i++){ the          while(Ll<rr&&jud (c[rr],c[rr-1],l[i]) rr--; the          while(Ll<rr&&jud (c[ll],c[ll+1],l[i]) ll++; -c[++rr]=L[i]; in     }  the      while(Ll<rr&&jud (c[rr],c[rr-1],C[LL]) rr--; the      while(Ll<rr&&jud (c[ll],c[ll+1],C[RR]) ll++;  About     if(rr-ll+1<3) {flag=1;return 0.00;} the     Doubleans=0; theCnt=0; thec[rr+1]=C[ll]; +      for(inti=ll;i<=rr;i++) -A[++cnt]=inter (c[i],c[i+1]); thea[cnt+1]=a[1];Bayi      for(intI=1; i<=cnt;i++) theans+=a[i]*a[i+1];  theAns/=2.0; -     returnfabs (ans); - } the intMain () { thep[0]=point (0,0); the     Chars[200005];Doublex,y;flag=0;intI=1; theL[++tot].s=point (0,Ten); L[tot].e=point (0,0); L[tot].slop=atan2 (l[tot].e.y-l[tot].s.y,l[tot].e.x-l[tot].s.x); -L[++tot].s=point (0,0); L[tot].e=point (Ten,0); L[tot].slop=atan2 (l[tot].e.y-l[tot].s.y,l[tot].e.x-l[tot].s.x); theL[++tot].s=point (Ten,0); L[tot].e=point (Ten,Ten); L[tot].slop=atan2 (l[tot].e.y-l[tot].s.y,l[tot].e.x-l[tot].s.x); theL[++tot].s=point (Ten,Ten); L[tot].e=point (0,Ten); L[tot].slop=atan2 (l[tot].e.y-l[tot].s.y,l[tot].e.x-l[tot].s.x); the      while(SCANF ("%LF%LF", &p[i].x,&p[i].y)! =EOF) {94scanf"%s", s+1); the         if(s[1]=='S') flag=1; the         if(flag) {Puts ("0.00");Continue;}  the         if(s[1]=='C'){98Point Mid= (p[i]+p[i-1])/2.0; AboutL[++tot].e=mid+turn (p[i]-p[i-1],pi/2.0); -l[tot].s=mid;101}Else{102Point Mid= (p[i]+p[i-1])/2.0;103L[++tot].e=mid+turn (p[i]-p[i-1],pi*3.0/2.0);104l[tot].s=mid; the         }106L[tot].slop=atan2 (l[tot].e.y-l[tot].s.y,l[tot].e.x-l[tot].s.x);107printf"%.2f\n", query ());108i++;109     } the}

POJ 2540 Hotter Colder