交叉比较List中的行数

Question

我是新手，如果你发现这个问题很愚蠢，我会要求耐心。但我真的需要帮助来解决这个问题。我有一个带有起点和终点的行列表，但是如果起点和终点与其他点的端点和起点相同，我需要消除一个。感谢那些愿意回答这个问题的人。这个网站对我很有帮助。

 private void sample()
    {
        SampleLine sl = new SampleLine();
        List<SampleLine> listLines = new List<SampleLine>();
        listLines.Add(new SampleLine { StartPoint = new Point(0, 250), EndPoint = new Point(150, 100)});    //[0]
        listLines.Add(new SampleLine { StartPoint = new Point(100, 350), EndPoint = new Point(250, 200) }); //[1]
        listLines.Add(new SampleLine { StartPoint = new Point(200, 500), EndPoint = new Point(350, 650) }); //[2]
        listLines.Add(new SampleLine { StartPoint = new Point(300, 550), EndPoint = new Point(450, 400) }); //[3]
        listLines.Add(new SampleLine { StartPoint = new Point(350, 650), EndPoint = new Point(200, 500) }); //[4]
        listLines.Add(new SampleLine { StartPoint = new Point(500, 750), EndPoint = new Point(650, 600) }); //[5]


        //From Above, index 2 and index 4 should be treated as the same and index 4 be deleted in the list
        /*
        listLines.Add(new SampleLine { StartPoint = new Point(200, 500), EndPoint = new Point(350, 650) }); //[2]
        listLines.Add(new SampleLine { StartPoint = new Point(350, 650), EndPoint = new Point(200, 500) }); //[4] startpoint[4] is equal to endpoint[2] and endpoint[4] is equal to startpoint[2]
        //index [4] should be deleted since it is cross equal with index[2]
        */
    }