201512-3 画图

我觉得这道题有两个难点吧，

1、坐标转化，原始坐标(i,j)，真实坐标应该转换为(rows - j - 1, i)

2、填充操作，使用递归填充，递归出口条件时下标越界或者遇到边界或者该位置已被填充，三个出口条件缺一不可

奉上java满分代码

import java.util.*;

public class Main {
    private static int rows, cols;
    private static char[][] canvas;

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String[] firstLine = scanner.nextLine().split(" ");
        cols = Integer.parseInt(firstLine[0]);
        rows = Integer.parseInt(firstLine[1]);

        canvas = new char[rows][cols];
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                canvas[i][j] = '.';
            }
        }

        for (int i = 0; i < Integer.parseInt(firstLine[2]); i++) {
            String[] line = scanner.nextLine().split(" ");
            boolean drawLine = Integer.parseInt(line[0]) == 0;
            if (drawLine) {
                int sx = rows - Integer.parseInt(line[2]) - 1;
                int sy = Integer.parseInt(line[1]);
                int ex = rows - Integer.parseInt(line[4]) - 1;
                int ey = Integer.parseInt(line[3]);
                drawLine(sx, sy, ex, ey);
            } else {
                int sx = rows - Integer.parseInt(line[2]) - 1;
                int sy = Integer.parseInt(line[1]);
                fill(sx, sy, line[3].charAt(0));
            }
        }

        scanner.close();


        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                System.out.print(canvas[i][j]);
            }
            System.out.println();
        }
    }


    private static void drawLine(int sx, int sy, int ex, int ey) {
        if (sx == ex) {
            int start = Math.min(sy, ey);
            int end = Math.max(sy, ey);
            for (int j = start; j <= end; j++) {
                if (canvas[sx][j] == '+')
                    continue;
                canvas[sx][j] = canvas[sx][j] == '|' ? '+' : '-';
            }
        } else {
            int start = Math.min(sx, ex);
            int end = Math.max(sx, ex);
            for (int i = start; i <= end; i++) {
                if (canvas[i][sy] == '+')
                    continue;
                canvas[i][sy] = canvas[i][sy] == '-' ? '+' : '|';
            }
        }
    }

    private static void fill(int i, int j, char ch) {
        if (i < 0 || i > rows - 1 || j < 0 || j > cols - 1)
            return;
        char val = canvas[i][j];
        if (val == '-' || val == '|' || val == '+' || val == ch)
            return;
        canvas[i][j] = ch;
        fill(i - 1, j, ch);
        fill(i + 1, j, ch);
        fill(i, j - 1, ch);
        fill(i, j + 1, ch);
    }

}