FZU2273Triangles+（三角形）+第八届福建省大学生程序设计竞赛

 Problem 2273 Triangles

Accept: 47    Submit: 115
Time Limit: 1000 mSec    Memory Limit : 262144 KB

 Problem Description

This is a simple problem. Given two triangles A and B, you should determine they are intersect, contain or disjoint. (Public edge or point are treated as intersect.)

 Input

First line contains an integer T (1 ≤ T ≤ 10), represents there are T test cases.

For each test case: X1 Y1 X2 Y2 X3 Y3 X4 Y4 X5 Y5 X6 Y6. All the coordinate are integer. (X1,Y1) , (X2,Y2), (X3,Y3) forms triangles A ; (X4,Y4) , (X5,Y5), (X6,Y6) forms triangles B.

-10000<=All the coordinate <=10000

 Output

For each test case, output “intersect”, “contain” or “disjoint”.

 Sample Input

20 0 0 1 1 0 10 10 9 9 9 100 0 1 1 1 0 0 0 1 1 0 1

 Sample Output

disjoint intersect

 Source

第八届福建省大学生程序设计竞赛-重现赛（感谢承办方厦门理工学院）

模板题

题意

给你两个三角形，判断是相交分离还是包含

思路

首先判断两个三角形是否相交，去判断边是否相交 http://blog.csdn.net/hyyjiushiliangxing/article/details/76010706

然后判断包含还是分离，去判断点在三角形内还是外  http://blog.csdn.net/hyyjiushiliangxing/article/details/76012954

#include<stdio.h>  #include <iostream>  #include <math.h>  using namespace std;  #define ABS_FLOAT_0 0.0001  double xx[88],yy[88];  struct node  {      double x, y;  } st1, ed1, st2, ed2;    struct point_float  {      float x;      float y;  };    double get_area(node a0, node a1, node a2)   //求有向面积  {      double s = a0.x*a1.y + a2.x*a0.y +a1.x*a2.y - a2.x*a1.y - a0.x*a2.y - a1.x*a0.y;      return s;  }    float GetTriangleSquar(const point_float pt0, const point_float pt1, const point_float pt2)  {      point_float AB,   BC;      AB.x = pt1.x - pt0.x;      AB.y = pt1.y - pt0.y;      BC.x = pt2.x - pt1.x;      BC.y = pt2.y - pt1.y;      return fabs((AB.x * BC.y - AB.y * BC.x)) / 2.0f;  }    bool IsInTriangle(const point_float A, const point_float B, const point_float C, const point_float D)  {      float SABC, SADB, SBDC, SADC;      SABC = GetTriangleSquar(A, B, C);      SADB = GetTriangleSquar(A, D, B);      SBDC = GetTriangleSquar(B, D, C);      SADC = GetTriangleSquar(A, D, C);        float SumSuqar = SADB + SBDC + SADC;        if ((-ABS_FLOAT_0 < (SABC - SumSuqar)) && ((SABC - SumSuqar) < ABS_FLOAT_0))      {          return true;      }      else      {          return false;      }  }      int pd()  {      double s1 = get_area(st1, ed1, st2);      double s2 = get_area(st1, ed1, ed2);      double s3 = get_area(st2, ed2, st1);      double s4 = get_area(st2, ed2, ed1);      if(s1 * s2 <= 0 && s3 * s4 <= 0)          return 1; //printf("Interseetion\n");      else          return 0;  //printf("Not Interseetion\n");  }      int main()  {      int t,flag,i,j,k,h;      scanf("%d",&t);      while(t--)      {          scanf("%lf %lf %lf %lf %lf %lf",&xx[1],&yy[1],&xx[2],&yy[2],&xx[3],&yy[3]);          scanf("%lf %lf %lf %lf %lf %lf",&xx[4],&yy[4],&xx[5],&yy[5],&xx[6],&yy[6]);          flag=0;          for(i=1; i<=3; i++)          {              st1.x=xx[i];              st1.y=yy[i];              for(k=1; k<=3; k++)              {                  if(k!=i)                  {                      ed1.x=xx[k];                      ed1.y=yy[k];                      for(j=4; j<=6; j++)                      {                          st2.x=xx[j];                          st2.y=yy[j];                          for(h=4; h<=6; h++)                          {                              if(h!=j)                              {                                  ed2.x=xx[h];                                  ed2.y=yy[h];                                  if(pd())                                  {                                      flag=1;                                      break;                                  }                              }                          }                      }                    }              }          }  //利用两线段是否相交 判断三角形是否相交          if(flag)          {              printf("intersect\n");              continue;          }            point_float A, B, C, P;          A.x =xx[1];          A.y =yy[1] ;          B.x =xx[2] ;          B.y =yy[2] ;          C.x =xx[3] ;          C.y =yy[3] ;         //判断三个点是否在三角形内          for(i=4; i<=6; i++)          {              P.x=xx[i];              P.y=yy[i];              if(IsInTriangle(A, B, C, P))              {                  flag=1;                  break;              }          }          if(flag)          {              printf("contain\n");              continue;          }          else printf("disjoint\n");      }      return 0;  }