UVA 4728 squares (convex hull + rotating jam)

Title Link: http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=17267

Ideas

Convex hull + rotating jam

The convex hull is obtained, and the diameter of the convex hull can be calculated by rotating the jam.

Code

1#include <cstdio>2#include <vector>3#include <iostream>4#include <algorithm>5 using namespacestd;6 7 structPt {8     intx, y;9Pt (intx=0,inty=0): X (x), Y (y) {};Ten }; One typedef Pt VEC; A  -Vecoperator-(Pt a,pt B) {returnVEC (a.x-b.x,a.y-b.y); } - BOOL operator< (Constpt& A,Constpt&b) { the     returna.x<b.x | | (a.x==b.x && a.y<b.y); - } - BOOL operator== (Constpt& A,Constpt&b) { -     returna.x==b.x && a.y==b.y; + } -  + intDot (VEC A,vec B) {returna.x*b.x+a.y+b.y;} A intCross (VEC A,vec B) {returna.x*b.y-a.y*b.x;} at intDist (Pt a,pt B) { -     return(a.x-b.x) * (a.x-b.x) + (A.Y-B.Y) * (a.y-b.y); - } -  - intN; -Vector<pt> Convexhull (vector<pt>p) { in sort (P.begin (), P.end ()); - p.erase (Unique (P.begin (), P.end ()), P.end ()); to     intn=p.size (); +     intm=0; -Vector<pt> CH (n+1); the      for(intI=0; i<n;i++) { *          while(m>1&& Cross (ch[m-1]-ch[m-2],p[i]-ch[m-2]) <=0) m--; $ch[m++]=P[i];Panax Notoginseng     } -     intk=m; the      for(inti=n-2; i>=0; i--) { +          while(M>k && Cross (ch[m-1]-ch[m-2],p[i]-ch[m-2]) <=0) m--; Ach[m++]=P[i]; the     } +     if(n>1) m--; - ch.resize (m); $     returnch; $ } -  - intDiameter (vector<pt> PS) {//Rotating Jam theVector<pt> p=Convexhull (PS); -     intn=p.size ();Wuyi     if(n==1)return 0;//Special Case Processing the     if(n==2)returnDist (p[0],p[1]); -P.push_back (p[0]);//For u Wu     intans=0; -      for(intu=0, v=1; u<n;u++) {                 About          for(;;) {             $             intDiff=cross (p[u+1]-p[u],p[v+1]-p[v]); -             if(diff<=0) {//at this point the UV is the heel point -ans=Max (Ans,dist (p[u],p[v)); -                 if(!diff) Ans=max (Ans,dist (p[u],p[v+1]));//Parallel A                  Break; +             } thev= (v+1)%N; -         } $     } the     returnans; the } the voidReadint&x) { the     CharC=GetChar (); -      while(!isdigit (c)) c=GetChar (); inx=0; the      while(IsDigit (c)) thex=x*Ten+c-'0', c=GetChar (); About }  the intMain () { the     intT; the read (T); +      while(t--) { -         intN; Read (n); theVector<pt>PS;Bayi          for(intI=0; i<n;i++) { the             intx,y,w; the Read (x), read ( y), read (w); - Ps.push_back (Pt (x, y)); -Ps.push_back (Pt (x+w,y)); thePs.push_back (Pt (x,y+W)); thePs.push_back (Pt (x+w,y+W)); the         } theprintf"%d\n", Diameter (PS)); -     } the     return 0; the}

UVA 4728 squares (convex hull + rotating jam)