Mark Mindrin's questions

我想根据给定的点构造一个多边形。为此，我执行格雷厄姆算法的第 1 点和第 2 点。接下来，我计划执行步骤 3，看看执行步骤 3 后点数组是否不同，因为如果是这样，那么我可以说最初多边形不是凸的。也就是说，我需要从位于随机坐标的随机数量的顶点构建一个多边形，然后判断构建的多边形是否是凸的。我受到这篇文章的启发：https://habr.com/ru/articles/144921/，但是，多边形尚未构建（我尚未开始第3步）。

我尝试了不同的方法，但最终选择了格雷厄姆的算法。显然，插入排序在其中无法正常工作，因为多边形的边有时会相交。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace TrueLab4_habrEdition
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        Graphics g;
        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            g = CreateGraphics();
            Random random = new Random();
            int z = random.Next(6, 8);
            Point[] points = new Point[z];
            int[,] pointsS = new int[z, 2];
            Point[] newPoints = new Point[z];
            int[] P = new int[z];

            // генерация точек
            for (int i = 0; i < z; i++)
            {
                int x = random.Next(50, 100);
                int y = random.Next(70, 170);
                points[i] = new Point(x, y);
            }

            // заполнение массива индексов точек
            for (int i = 0; i < z; i++)
            {
                P[i] = i;
            }

            // копирование массива points в pointsS
            for (int i = 0; i < z; i++)
            {
                pointsS[i, 0] = points[i].X;
                pointsS[i, 1] = points[i].Y;
            }

            grahamscan(pointsS, P);

            int j = 0;
            for (int i = 0; i < P.Length; i++)
            { 
                int x = pointsS[P[i], 0];
                int y = pointsS[P[i], 1];
                newPoints[j++] = new Point(x, y);
                Console.WriteLine(P[i]);
            }
            show2d(pointsS);
            Pen pen = new Pen(Color.Red, 1);
            g.DrawPolygon(pen, newPoints);
        }
        void grahamscan(int[,] pointsS, int[]P)
        {
            for (int i = 1; i < pointsS.GetLength(0); i++) 
            {
                if (pointsS[P[i], 0] < pointsS[0, 0])
                {
                    (P[i], P[0]) = (P[0], P[i]);
                }
            }
            for (int i = 2; i < pointsS.GetLength(0); i++)
            {
                int j = i;
                int[] a = { pointsS[P[0], 0], pointsS[P[0], 1] };
                int[] b = { pointsS[P[j-1], 0], pointsS[P[j-1], 1] };
                int[] c = { pointsS[P[j], 0], pointsS[P[j], 1] };
                while (j > 1 && rotate(a, b, c) < 0)
                {
                    (P[j], P[j-1]) = (P[j-1], P[j]);
                    j -= 1;
                }
            }
        }
        double rotate(int[] A, int[] B, int[] C)
        {
            return (B[0] - A[0]) * (C[1] - B[1]) - (B[1] - A[1]) * (C[0] - B[0]);
        }

        void show2d(int[,] p)
        {
            for (int i = 0; i < p.GetLength(0); i++)
            {
                for (int j = 0; j < p.GetLength(1); j++)
                {
                    Console.Write(p[i, j] + "\t");
                }
                Console.WriteLine();
            }
        }
    }
}

在此输入图像描述

public static String[][] toMatrix(List<String> data) {
    return data.stream()
        .map(str -> str.chars().mapToObj(e -> (char)e).collect(Collectors.toList()).stream().toArray(String[]::new))
        .toArray(String[][]::new);
} 

代码应该来自["aaa", "bbb", "ccc"]make[[a,a,a], [b,b,b], [c,c,c]]

创建 2D ArrayList：

ArrayList<String> map = new ArrayList<String>();
BufferedReader reader;
try {
    reader = new BufferedReader(new FileReader("map.txt"));
    String line = reader.readLine();
    while (line != null) {
        map.add(new String(line.strip()));
        line = reader.readLine();
    }
    reader.close();
} catch (IOException e) {
    e.printStackTrace();
}

我尝试以与JavaRush 文章中相同的方式转换为数组：

String[][] zzz = map.toArray(new String[map.size()][map.get(0).length()]);

static void BFS(ArrayList<String> map, int [] s, int [] t){
    int n = map.size();
    int m = map.get(0).length();
    final int INF = (int) Math.pow(10, 9);
    int [][] delta = {{0, -1}, {0, 1}, {1, 0}, {-1, 0}};
    int[][]arrayINFmap = new int[n][m];
    for(int i = 0; i < n; i++){
        for(int j = 0; j < m; j++){
            arrayINFmap[i][j] = INF;
        }
    }
    String[][]arrayTFmap = new String[n][m];
    for(int i = 0; i < n; i++){
        for(int j = 0; j < m; j++){
            arrayTFmap[i][j] = "False";
        }
    }
    // проблема тут
    ArrayDeque<List> deque = new ArrayDeque<>();
    arrayINFmap[s[0]][s[1]] = 0;
    arrayTFmap[s[0]][s[1]] = "True";
    deque.add(Arrays.asList(s));
    while (deque.size() != 0){
        int x = deque.peekFirst().get(0);
        int y = deque.peekFirst().get(1);
    }
}

тут проблема в том, что get возвращает Object. А мне int нужен