LA 2402 (enum) fishnet

Test instructions

There are n points on the four boundaries of a square, dividing it into (n+1) 2 quads, and finding the maximum of the quadrilateral area.

Analysis:

Because n is small in size, you can double-loop the enumeration to find the maximum value.

To find the intersection point of a line (a, 0) (b, 0) and a straight line (0, C) (0, D), I am the solution of the two-tuple equation, and then we use the cross-product to find the area.

1#include <cstdio>2#include <cstring>3#include <cmath>4#include <algorithm>5 6 Const intMAXN = -+Ten;7 structHEHE8 {9     DoubleA, B, C, D;Ten }HEHE[MAXN]; One  A struct Point - { -     Doublex, y; thePoint (Doublex=0,Doubley=0): X (x), Y (y) {} - }; - typedef point Vector; -  +Vectoroperator- (Constvector& A,Constvector&B) -{returnVector (a.x-b.x, A.Y-b.y); } +  A DoubleCross (Constvector& A,Constvector&B) at{return(a.x*b.y-a.y*b.x); } -  -Point Getintersection (Const Double& A,Const Double& B,Const Double& C,Const Double&d) - { -     Doublex = (A + (B-A) *c)/(1-(B-A) * (dc)); -     Doubley = (d-c) *x+C; in     returnPoint (x, y); - } to  + intMainvoid) - { the     //freopen ("2402in.txt", "R", stdin); *      $     intN;Panax Notoginseng      while(SCANF ("%d", &n) = =1&&N) -     { thememset (hehe,0,sizeof(hehe)); +          for(inti =1; I <= N; ++i) scanf ("%LF", &hehe[i].a); A          for(inti =1; I <= N; ++i) scanf ("%LF", &hehe[i].b); the          for(inti =1; I <= N; ++i) scanf ("%LF", &hehe[i].c); +          for(inti =1; I <= N; ++i) scanf ("%LF", &hehe[i].d); -hehe[n+1].A = hehe[n+1].b = hehe[n+1].C = hehe[n+1].D =1.0; $          $         DoubleAns =0.0; -          for(inti =0; I <= N; ++i) -              for(intj =0; J <= N; ++j) the             { - Point A, B, C, D;WuyiA =getintersection (hehe[i].a, hehe[i].b, hehe[j].c, HEHE[J].D); theB = Getintersection (hehe[i+1].A, hehe[i+1].b, HEHE[J].C, HEHE[J].D); -C = Getintersection (hehe[i+1].A, hehe[i+1].B, hehe[j+1].C, hehe[j+1].d); WuD = Getintersection (hehe[i].a, hehe[i].b, hehe[j+1].C, hehe[j+1].d); -                 Doubletemp =0.0; Abouttemp + = Cross (b-a, c-a)/2; $temp + = Cross (c-a, d-a)/2; -Ans =Std::max (ans, temp); -             } -              Aprintf"%.6f\n", ans); +     } the      -     return 0; $}

code June

LA 2402 (enum) fishnet