USACO_3_1_Shaping Regions

做一个矩形类，然后模拟放的过程，不过从最后放的矩形开始反序考虑

比如题目给出的样例，一开始放入颜色4的矩形，得到4与1相交部分，然后无论前面的矩形怎么放这一部分的颜色都是4，此时把其余颜色为1的部分分解为3个小矩形

然后再考虑放下颜色3的矩形，考虑剩余的白色矩形（颜色1），把每一个与3相交的做同样处理，即先把相交部分涂成颜色3，把这个白色矩形的其它部分分解为多个小矩形

直到放入第一个矩形为止

代码用一个RectangleList类来存放所有的白色矩形（由“白纸”分解而得）

Code
/**//*
ID: sdjllyh1
PROG: rect1
LANG: JAVA
complete date: 2009/1/8
author: LiuYongHui From GuiZhou University Of China
more articles: www.cnblogs.com/sdjls
*/

import java.io.*;
import java.util.*;

public class rect1
{
    public static int n;//要放的矩形个数
    public static int[] l, r, t, b, c;//每个矩形的left,right,top,bottom,color
    public static int[] color = new int[2501];//每种颜色的面积

    public static void main(String[] args) throws IOException
    {
        init();
        run();
        output();
        System.exit(0);
    }

    private static void run()
    {
        //把白纸放入矩形链中
        RectangleList rects = new RectangleList(new Rectangle(t[0], b[0], l[0], r[0], 1));
        //从最后放入的矩形开始依次考虑放入每一个矩形
        for (int i = n; i > 0; i--)
        {
            //获得放入的矩形
            Rectangle laying = new Rectangle(t[i], b[i], l[i], r[i], c[i]);
            //获得与laying重叠的白色矩形
            List overlaps = rects.overlapRectangles(laying);
            Iterator it = overlaps.iterator();
            //依次考虑每一个白色矩形
            while (it.hasNext())
            {
                //获得当前考虑的白色矩形
                Rectangle overlap = (Rectangle)it.next();
                //laying的颜色面积增加，增加的面积是它与当前白色矩形重叠的面积
                color[laying.color] += laying.overlapArea(overlap);
                //用laying把当前白色矩形分解为length个矩形，重叠部分不要
                Rectangle[] deRects = laying.decompose(overlap);
                if (deRects != null)
                {
                    int length = deRects.length;
                    //把分解得到的小矩形加入集合中
                    for (int j = 0; j < length; j++)
                    {
                        rects.insertRect(deRects[j]);
                    }
                }
                //从集合中删除当前白色矩形
                rects.deleteRect(overlap);
            }
        }
        //计算白色面积
        color[1] = r[0] * t[0];
        for (int i = 2; i <= 2500; i++)
        {
            color[1] -= color[i];
        }

    }

    private static void init() throws IOException
    {
        BufferedReader f = new BufferedReader(new FileReader("rect1.in"));
        char[] buff = new char[40000];
        f.read(buff);
        StringTokenizer st = new StringTokenizer(String.valueOf(buff));

        int right = Integer.parseInt(st.nextToken());
        int top = Integer.parseInt(st.nextToken());
        n = Integer.parseInt(st.nextToken());
        l = new int[n+1];
        r = new int[n+1];
        t = new int[n+1];
        b = new int[n+1];
        c = new int[n+1];

        r[0] = right;
        t[0] = top;

        for (int i = 1; i <= n; i++)
        {
            l[i] = Integer.parseInt(st.nextToken());
            b[i] = Integer.parseInt(st.nextToken());
            r[i] = Integer.parseInt(st.nextToken());
            t[i] = Integer.parseInt(st.nextToken());
            c[i] = Integer.parseInt(st.nextToken());
        }
        f.close();
    }

    private static void output() throws IOException
    {
        PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("rect1.out")));
        for (int i = 1; i <= 2500; i++)
        {
            if (color[i] > 0)
            {
                out.print(i);
                out.print(' ');
                out.println(color[i]);
            }
        }
        out.close();
    }
}
//矩形类
class Rectangle
{
    private int top, bottom, left, right;//四条边坐标
    public int color;//颜色
    
    public Rectangle(int top, int bottom, int left, int right, int color)
    {
        this.top = top;
        this.bottom = bottom;
        this.left = left;
        this.right = right;
        this.color = color;
    }
    //分解rect矩形，获得多个小矩形，不要重叠部分
    public Rectangle[] decompose(Rectangle rect)
    {
        Rectangle[] retList = null;
        int color = rect.color;
        int length;
        //如果右在中间
        if ((rect.right <= this.right) && (rect.right >= this.left))
        {
            //如果左在中间
            if ((rect.left <= this.right) && (rect.left >= this.left))
            {
                //===右、左都在中间
                //如果上在中间
                if ((rect.top <= this.top) && (rect.top >= this.bottom))
                {
                    //如果下在中间
                    if ((rect.bottom <= this.top) && (rect.bottom >= this.bottom))
                    {
                        //===上下左右都在中间
                    }
                    else
                    {
                        //===左、右、上在中间、下不在
                        length = 1;
                        Rectangle[] dr = new Rectangle[length];
                        retList = dr;
                        int[] l = new int[length];
                        int[] r = new int[length];
                        int[] t = new int[length];
                        int[] b = new int[length];

                        l[0] = rect.left; r[0] = rect.right; t[0] = this.bottom; b[0] = rect.bottom;

                        for (int i = 0; i < length; i++)
                            dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
                    }
                }//如果下在中间
                else if ((rect.bottom <= this.top) && (rect.bottom >= this.bottom))
                {
                    //===左右下都在、上不在
                    length = 1;
                    Rectangle[] dr = new Rectangle[length];
                    retList = dr;
                    int[] l = new int[length];
                    int[] r = new int[length];
                    int[] t = new int[length];
                    int[] b = new int[length];

                    l[0] = rect.left; r[0] = rect.right; t[0] = rect.top; b[0] = this.top;

                    for (int i = 0; i < length; i++)
                        dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
                }
                else if ((rect.top >= this.top) && (rect.bottom <= this.bottom))
                {
                    //===左右在中间、上下在两边
                    length = 2;
                    Rectangle[] dr = new Rectangle[length];
                    retList = dr;
                    int[] l = new int[length];
                    int[] r = new int[length];
                    int[] t = new int[length];
                    int[] b = new int[length];

                    l[0] = rect.left; r[0] = rect.right; t[0] = rect.top; b[0] = this.top;
                    l[1] = rect.left; r[1] = rect.right; t[1] = this.bottom; b[1] = rect.bottom;

                    for (int i = 0; i < length; i++)
                        dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
                }
            }
            else
            {
                //===右在中间，左不在中间
                //如果上在中间
                if ((rect.top <= this.top) && (rect.top >= this.bottom))
                {
                    //如果下在中间
                    if ((rect.bottom <= this.top) && (rect.bottom >= this.bottom))
                    {
                        //===右、上、下在中间、左不在
                        length = 1;
                        Rectangle[] dr = new Rectangle[length];
                        retList = dr;
                        int[] l = new int[length];
                        int[] r = new int[length];
                        int[] t = new int[length];
                        int[] b = new int[length];

                        l[0] = rect.left; r[0] = this.left; t[0] = rect.top; b[0] = rect.bottom;

                        for (int i = 0; i < length; i++)
                            dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
                    }
                    else
                    {
                        //===右、上在，左、下不在
                        length = 2;
                        Rectangle[] dr = new Rectangle[length];
                        retList = dr;
                        int[] l = new int[length];
                        int[] r = new int[length];
                        int[] t = new int[length];
                        int[] b = new int[length];

                        l[0] = rect.left; r[0] = this.left; t[0] = rect.top; b[0] = rect.bottom;
                        l[1] = this.left; r[1] = rect.right; t[1] = this.bottom; b[1] = rect.bottom;

                        for (int i = 0; i < length; i++)
                            dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
                    }
                }
                else if ((rect.bottom <= this.top) && (rect.bottom >= this.bottom))
                {
                    //===右、下在中间，上、左不在中间
                    length = 2;
                    Rectangle[] dr = new Rectangle[length];
                    retList = dr;
                    int[] l = new int[length];
                    int[] r = new int[length];
                    int[] t = new int[length];
                    int[] b = new int[length];

                    l[0] = rect.left; r[0] = this.left; t[0] = rect.top; b[0] = rect.bottom;
                    l[1] = this.left; r[1] = rect.right; t[1] = rect.top; b[1] = this.top;

                    for (int i = 0; i < length; i++)
                        dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
                }
                else
                {
                    //===右在、上下左不在
                    length = 3;
                    Rectangle[] dr = new Rectangle[length];
                    retList = dr;
                    int[] l = new int[length];
                    int[] r = new int[length];
                    int[] t = new int[length];
                    int[] b = new int[length];

                    l[0] = rect.left; r[0] = this.left; t[0] = rect.top; b[0] = rect.bottom;
                    l[1] = this.left; r[1] = rect.right; t[1] = rect.top; b[1] = this.top;
                    l[2] = this.left; r[2] = rect.right; t[2] = this.bottom; b[2] = rect.bottom;

                    for (int i = 0; i < length; i++)
                        dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
                }
            }
        }
        else if ((rect.left <= this.right) && (rect.left >= this.left))
        {
            //===右不在中间、左在中间
            //如果上在中间
            if ((rect.top <= this.top) && (rect.top >= this.bottom))
            {
                //===左、上在中间，右不在
                //如果下在中间
                if ((rect.bottom <= this.top) && (rect.bottom >= this.bottom))
                {
                    //===左、上、下在中间，右不在
                    length = 1;
                    Rectangle[] dr = new Rectangle[length];
                    retList = dr;
                    int[] l = new int[length];
                    int[] r = new int[length];
                    int[] t = new int[length];
                    int[] b = new int[length];

                    l[0] = this.right; r[0] = rect.right; t[0] = rect.top; b[0] = rect.bottom;

                    for (int i = 0; i < length; i++)
                        dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
                }
                else
                {
                    //===左上在，右下不在
                    length = 2;
                    Rectangle[] dr = new Rectangle[length];
                    retList = dr;
                    int[] l = new int[length];
                    int[] r = new int[length];
                    int[] t = new int[length];
                    int[] b = new int[length];

                    l[0] = rect.left; r[0] = this.right; t[0] = this.bottom; b[0] = rect.bottom;
                    l[1] = this.right; r[1] = rect.right; t[1] = rect.top; b[1] = rect.bottom;

                    for (int i = 0; i < length; i++)
                        dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
                }
            }
            else if ((rect.bottom <= this.top) && (rect.bottom >= this.bottom))
            {
                //===下、左在中间，右、上不在中间
                length = 2;
                Rectangle[] dr = new Rectangle[length];
                retList = dr;
                int[] l = new int[length];
                int[] r = new int[length];
                int[] t = new int[length];
                int[] b = new int[length];

                l[0] = rect.left; r[0] = this.right; t[0] = rect.top; b[0] = this.top;
                l[1] = this.right; r[1] = rect.right; t[1] = rect.top; b[1] = rect.bottom;

                for (int i = 0; i < length; i++)
                    dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
            }
            else
            {
                //===左在，右上下不在
                length = 3;
                Rectangle[] dr = new Rectangle[length];
                retList = dr;
                int[] l = new int[length];
                int[] r = new int[length];
                int[] t = new int[length];
                int[] b = new int[length];

                l[0] = rect.left; r[0] = this.right; t[0] = rect.top; b[0] = this.top;
                l[1] = rect.left; r[1] = this.right; t[1] = this.bottom; b[1] = rect.bottom;
                l[2] = this.right; r[2] = rect.right; t[2] = rect.top; b[2] = rect.bottom;

                for (int i = 0; i < length; i++)
                    dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
            }
        }
        else
        {
            //===左右都不在中间
            if ((rect.top <= this.top) && (rect.top >= this.bottom))
            {
                //===如果上在、左右不在
                if ((rect.bottom <= this.top) && (rect.bottom >= this.bottom))
                {
                    //===上、下在，左右不在
                    length = 2;
                    Rectangle[] dr = new Rectangle[length];
                    retList = dr;
                    int[] l = new int[length];
                    int[] r = new int[length];
                    int[] t = new int[length];
                    int[] b = new int[length];

                    l[0] = rect.left; r[0] = this.left; t[0] = rect.top; b[0] = rect.bottom;
                    l[1] = this.right; r[1] = rect.right; t[1] = rect.top; b[1] = rect.bottom;

                    for (int i = 0; i < length; i++)
                        dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
                }
                else
                {
                    //===上在，左右下不在
                    length = 3;
                    Rectangle[] dr = new Rectangle[length];
                    retList = dr;
                    int[] l = new int[length];
                    int[] r = new int[length];
                    int[] t = new int[length];
                    int[] b = new int[length];

                    l[0] = rect.left; r[0] = this.left; t[0] = rect.top; b[0] = rect.bottom;
                    l[1] = this.left; r[1] = this.right; t[1] = this.bottom; b[1] = rect.bottom;
                    l[2] = this.right; r[2] = rect.right; t[2] = rect.top; b[2] = rect.bottom;

                    for (int i = 0; i < length; i++)
                        dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
                }
            }
            else
            {
                //===左右上都不在
                if ((rect.bottom <= this.top) && (rect.bottom >= this.bottom))
                {
                    //===下在，左右上不在
                    length = 3;
                    Rectangle[] dr = new Rectangle[length];
                    retList = dr;
                    int[] l = new int[length];
                    int[] r = new int[length];
                    int[] t = new int[length];
                    int[] b = new int[length];

                    l[0] = rect.left; r[0] = this.left; t[0] = rect.top; b[0] = rect.bottom;
                    l[1] = this.left; r[1] = this.right; t[1] = rect.top; b[1] = this.top;
                    l[2] = this.right; r[2] = rect.right; t[2] = rect.top; b[2] = rect.bottom;

                    for (int i = 0; i < length; i++)
                        dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
                }
                else
                {
                    //===上下左右都不在
                    length = 4;
                    Rectangle[] dr = new Rectangle[length];
                    retList = dr;
                    int[] l = new int[length];
                    int[] r = new int[length];
                    int[] t = new int[length];
                    int[] b = new int[length];

                    l[0] = rect.left; r[0] = this.left; t[0] = rect.top; b[0] = rect.bottom;
                    l[1] = this.left; r[1] = this.right; t[1] = rect.top; b[1] = this.top;
                    l[2] = this.right; r[2] = rect.right; t[2] = rect.top; b[2] = rect.bottom;
                    l[3] = this.left; r[3] = this.right; t[3] = this.bottom; b[3] = rect.bottom;

                    for (int i = 0; i < length; i++)
                        dr[i] = new Rectangle(t[i], b[i], l[i], r[i], color);
                }
            }
        }
        return retList;
    }
    //判断矩形是否重叠
    public boolean isOverlap(Rectangle rect)
    {
        int l = Math.max(this.left, rect.left);
        int r = Math.min(this.right, rect.right);
        if (l >= r)
            return false;

        int b = Math.max(this.bottom, rect.bottom);
        int t = Math.min(this.top, rect.top);
        if (b >= t)
            return false;

        return true;
    }
    //计算重叠面积
    public int overlapArea(Rectangle rect)
    {
        int l = Math.max(this.left, rect.left);
        int r = Math.min(this.right, rect.right);
        if (l >= r)
            return 0;

        int b = Math.max(this.bottom, rect.bottom);
        int t = Math.min(this.top, rect.top);
        if (b >= t)
            return 0;

        int wide = r - l;
        int hight = t - b;

        return wide * hight;
    }
};//class Rectangle end

//矩形链表
class RectangleList
{
    private List listRect = new ArrayList();

    public RectangleList(Rectangle rect)
    {
        listRect.add(rect);
    }
    //插入矩形
    public void insertRect(Rectangle rect)
    {
        listRect.add(rect);
    }
    //删除矩形
    public void deleteRect(Rectangle rect)
    {
        listRect.remove(rect);
    }
    //返回链中所有与rect重叠的矩形
    public List overlapRectangles(Rectangle rect)
    {
        List retList = new ArrayList();

        Iterator it = listRect.iterator();
        while (it.hasNext())
        {
            Rectangle r = (Rectangle)it.next();
            if (rect.isOverlap(r))
            {
                retList.add(r);
            }
        }

        return retList;
    }
};//class RectangleList end