华为机试题：判断一个点是否在三角形内（java）

怼烎@ 2022-08-20 10:21 169阅读 0赞

<table style="margin:0px; padding:0px; width:970px; border:0px; border-collapse:collapse; border-spacing:0px; empty-cells:show; color:rgb(0,0,0); font-family:'Times New Roman',Arial,微软雅黑,宋体,Tahoma,Helvetica,SimSun,sans-serif,宋体"> 
 <tbody style="margin:0px; padding:0px"> 
 <tr style="margin:0px; padding:0px; height:26px"> 
 <td style="margin:0px; padding:6px 3px 3px; word-break:break-all; word-wrap:break-word; border-right-style:solid; border-right-width:1px; border-right-color:rgb(238,238,238); font-size:14px; border-bottom-style:solid; border-bottom-width:1px; border-bottom-color:rgb(238,238,238)"> 描述:&nbsp;</td> 
 <td style="margin:0px; padding:6px 3px 3px; word-break:break-all; word-wrap:break-word; font-size:14px; border-bottom-style:solid; border-bottom-width:1px; border-bottom-color:rgb(238,238,238)"> 一个二维坐标系中（100*100，每一维0~99），已知三角形三个顶点的坐标A、B、C，判断坐标系中的任意点：P，是否在三角形内（在三角形边上也认为在三角形内） &nbsp; 请实现如下接口 /*&nbsp;功能：点是否在三角形内 &nbsp;*&nbsp;输入：三角形三顶点坐标：A、B、C，以及待确认的点：P &nbsp;*&nbsp;输出：无 &nbsp;*&nbsp;返回：在三角形内返回true，否则返回false &nbsp;*/ public&nbsp;static&nbsp;boolean&nbsp;isInTriangle(POINTA,&nbsp;POINTB,&nbsp;POINTC,&nbsp;POINTP) { &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;true; } &nbsp; &nbsp; 约束： 
 <ol style="margin:0px; padding:0px"> 
 <li style="margin:0px; padding:0px"> 二维坐标系中（100*100，每一维0~99），接口传入4点坐标的合法性由调用者保证 </li> 
 <li style="margin:0px; padding:0px"> &nbsp; </li> 
 </ol> &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;</td> 
 </tr> 
 </tbody> 
</table>

package huawei;
 
 import java.math.*;
 
 public final class Demo {
 	
 	
 	
 	@SuppressWarnings("null")
 	public static boolean isInTriangle(POINT A, POINT B, POINT C, POINT P)
 	{
 		 /*利用叉乘法进行判断,假设P点就是M点*/
 		int a = 0, b = 0, c = 0;
 		
 		/*向量减法*/
 		POINT MA = new POINT(P.x - A.x,P.y - A.y);
 		POINT MB = new POINT(P.x - B.x,P.y - B.y);
 		POINT MC = new POINT(P.x - C.x,P.y - C.y);
 		
 		/*向量叉乘*/
 		a = MA.x * MB.y - MA.y * MB.x;
 		b = MB.x * MC.y - MB.y * MC.x;
 		c = MC.x * MA.y - MC.y * MA.x;
 		
 		if((a <= 0 && b <= 0 && c <= 0)||
 			(a > 0 && b > 0 && c > 0))
 		{
 			return true;
 		}
 		
 		return false;
 	}
 }

package huawei;
    
    public class POINT {
    	int x;
    	int y;
    	public POINT(int x,int y)
    	{
    		this.x=x;
    		this.y=y;
    	}
    }