2017acm福建省赛FZU 2273 Triangles

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Problem 2273 Triangles

Accept: 34 Submit: 82
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

0 0 0 1 1 0 10 10 9 9 9 10

0 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）

http://acm.fzu.edu.cn/problem.php?pid=2273

判断两个三角形是内含还是相交还是分离

什么都不说直接上模板吧

#include<stdio.h>#include <iostream>#include <math.h>using namespace std;#define ABS_FLOAT_0 0.0001double 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;            }        }        //再判断A在B里面吗        A.x =xx[4];        A.y =yy[4] ;        B.x =xx[5] ;        B.y =yy[5] ;        C.x =xx[6] ;        C.y =yy[6] ;       //判断三个点是否在三角形内        for(i=1; i<=3; 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;}

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