/*** @date  2015年9月16日*/
package geometry;import java.util.Scanner;public class Segment {/*** 返回向量：(pi-pk)*(pi-pj) 的叉积* pi, pj, pk, 分别是平面上的三点坐标，* pi[0] -> x* pi[1] -> y* @return int*/private int direction(int[] pi, int[] pj, int[] pk){return (pi[0]-pk[0])*(pi[1]-pj[1]) - (pi[0]-pj[0])*(pi[1]-pk[1]);}/*** 判断点pk是否在线段 pi,pj 上* @return boolean*/private boolean onSegment(int[] pi, int[] pj, int[] pk) {if ( Math.min(pi[0], pj[0]) <= pk[0] && pk[0] <= Math.max(pi[0], pj[0]) && Math.min(pi[1], pj[1]) <= pk[1] && pk[1] <= Math.max(pi[1], pj[1]) ) {return true;}else {return false;}}// 判断线段 p1,p2 和线段 p3,p4 是否相交public boolean segmentInsert(int[] p1, int[] p2, int[] p3, int[] p4) {int d1 = direction(p3, p4, p1);int d2 = direction(p3, p4, p2);int d3 = direction(p1, p2, p3);int d4 = direction(p1, p2, p4);if ( ((d1>0 && d2<0) || (d1<0 && d2>0)) &&((d3>0 && d4<0) || (d3<0 && d4>0))) {return true;} else if ( d1==0 && onSegment(p3, p4, p1)) {return true;} else if ( d2==0 && onSegment(p3, p4, p2)) {return true;} else if ( d3==0 && onSegment(p1, p2, p3)) {return true;} else if ( d4==0 && onSegment(p1, p2, p4)) {return true;} else {return false;}}public static void main(String[] args){Segment segment = new Segment();Scanner in = new Scanner(System.in);int[] p1 = {in.nextInt(), in.nextInt()};int[] p2 = {in.nextInt(), in.nextInt()};int[] p3 = {in.nextInt(), in.nextInt()};int[] p4 = {in.nextInt(), in.nextInt()};if (segment.segmentInsert(p1, p2, p3, p4)) {System.out.println("相交");} else {System.out.println("不相交");}}
}