P1355 Mysterious Grand Triangle

Title Description

Determines the position relationship of a point to a known triangle.

Input output Format input format:

First three lines: one coordinate per line representing the three vertices of the triangle

Line four: The coordinates of a point, try to determine the location of the point and the first three points around the triangle position relationship

(See examples)

All coordinate values are integers.

Output format:

If the point is within the triangle (excluding the boundary), the output is 1;

If the point is outside the triangle (excluding the boundary), the output is 2;

If the point is on the triangle boundary (without vertices), the output is 3;

If the point is on the triangle vertex, output 4.

Input and Output Sample input example # #:

(0,0) (3,0) (0,3) (a)

Sample # # of output:

1

Description

"Data size and conventions"

For 100% data, 0<= the horizontal and vertical coordinates of all points <=100

The data is weak, how can the public engage in a. Just practice your train of thought.

//The AC code of his own brain hole#include <cstdio>#include<cmath>using namespacestd;intRead () {intx=0, f=1;CharCh=GetChar ();  while(ch<'0'|| Ch>'9'){if(ch=='-') f=-1; ch=GetChar ();}  while(ch>='0'&&ch<='9') {x=x*Ten+ch-'0'; ch=GetChar ();} returnx*F;}Const DoublePi=acos (-1);structnode{intx, y; BOOL operator==(ConstNode &a) {        returnx==a.x&&y==a.y; }}a,b,c,d;voidinit () {a.x=read (); a.y=read (); b.x=read (); b.y=read (); c.x=read (); c.y=read (); D.x=read ();D. y=read ();}DoubleSlop (node A,node b) {if(a.x==b.x)return1e9; return(Double) (A.Y-B.Y)/(Double) (a.x-b.x);}BOOLDeal (node A,node b) {//High Accuracy Requirementsnode t1,t2; t1.x=a.x-d.x;t1.y=a.y-D.y; t2.x=b.x-d.x;t2.y=b.y-D.y; DoubleXiang= (Double) (t1.x*t2.x+t1.y*t2.y); DoubleMo=sqrt ((T1.X*T1.X+T1.Y*T1.Y) * (t2.x*t2.x+t2.y*t2.y)); Doublecita=xiang/mo; if(ACOs (CITA) ==pi)return 1; Else return 0;}voidWork () {if(d==a| | d==b| | D==c) {puts ("4");return ;} //dot product seeking angle 180 common line    if(Deal (A, b)) {Puts ("3");return ;} if(Deal (A,C)) {Puts ("3");return ;} if(Deal (B,C)) {Puts ("3");return ;} //determine if the point is in the triangle//http://files.cnblogs.com/files/shenben/%E5%88%A4%E6%96%AD%E7%82%B9%E6%98%AF%E5%90%A6%E5%9C%A8%E4%B8%89%E8% A7%92%e5%bd%a2%e4%b8%ad.sh    if(Slop (A, B)!=slop (a,c) &&slop (a,d)! =Slop (b,c)&& (Slop (a,d)-slop (A, B)) * (a.x-b.x) * (Slop (a,d)-slop (a,c)) * (a.x-c.x) <=0&& (Slop (a,d)-slop (b,c)) * (a.x-d.x) * (Slop (b,d)-slop (b,c)) * (b.x-d.x) <0) {puts ("1"); }    ElsePuts"2");}intMain () {init ();    Work (); return 0;}

//a better idea of the AC code#include <cstdio>#include<cstdlib>#include<cmath>using namespacestd;intRead () {intx=0, f=1;CharCh=GetChar ();  while(ch<'0'|| Ch>'9'){if(ch=='-') f=-1; ch=GetChar ();}  while(ch>='0'&&ch<='9') {x=x*Ten+ch-'0'; ch=GetChar ();} returnx*F;}structnode{intx, y; BOOL operator==(ConstNode &a) {        returnx==a.x&&y==a.y; }}a,b,c,d;voidinit () {a.x=read (); a.y=read (); b.x=read (); b.y=read (); c.x=read (); c.y=read (); D.x=read ();D. y=read ();}intCalcConstNode &a,ConstNode &b,ConstNode &c) {//Cross product    returnABS ((A.X*B.Y+B.X*C.Y+C.X*A.Y)-(a.x*c.y+b.x*a.y+c.x*b.y));}voidWork () {if(d==a| | d==b| | D==c) puts ("4"); Else{//Low Accuracy Requirements        if(Calc (d,a,b) +calc (d,a,c) +calc (d,b,c)!=calc (a,b,c)) puts ("2");//range, must be outside the triangle        Else if(!calc (d,a,b) | |! Calc (d,a,c) | |! Calc (d,b,c)) puts ("3");//cross Product = 0, on the line segment (not rigorous ...)        ElsePuts"1");//only inside the triangle .    } }intMain () {init ();    Work (); return 0;}

P1355 Mysterious Grand Triangle