Poj 3695-Rectangles 矩形切割

Rectangles

Time Limit: 2000MS		Memory Limit: 65536K
Total Submissions: 3846		Accepted: 1124

Description

You are developing a software for painting rectangles on the screen. The software supports drawing several rectangles and filling some of them with a color different from the color of the background. You are to implement an important function. The function answer such queries as what is the colored area if a subset of rectangles on the screen are filled.

Input

The input consists of multiple test cases. Each test case starts with a line containing two integers N(1 ≤ N ≤ 20) and M(1 ≤ M ≤ 100000), indicating the number of rectangles on the screen and the number of queries, respectively.
The i-th line of the following N lines contains four integers X₁,Y₁,X₂,Y₂ (0 ≤ X₁ < X₂ ≤ 1000, 0 ≤ Y1 < Y2 ≤ 1000), which indicate that the lower-left and upper-right coordinates of the i-th rectangle are (X₁, Y₁) and (X₂,Y₂). Rectangles are numbered from 1 to N.
The last M lines of each test case describe M queries. Each query starts with a integer R(1<=R ≤ N), which is the number of rectangles the query is supposed to fill. The following list of R integers in the same line gives the rectangles the query is supposed to fill, each integer of which will be between 1 and N, inclusive.

The last test case is followed by a line containing two zeros. 

Output

For each test case, print a line containing the test case number( beginning with 1).
For each query in the input, print a line containing the query number (beginning with 1) followed by the corresponding answer for the query. Print a blank line after the output for each test case. 

Sample Input

2  2
0 0 2 2
1 1 3 3
1 1
2 1 2
2 1
0 1 1 2
2 1 3 2
2 1 2
0 0

Sample Output

Case 1:
Query 1: 4
Query 2: 7

Case 2:
Query 1: 2

Source

2008 Asia Hefei Regional Contest Online by USTC

题意：给你一些矩形，编号为1~n。有一些询问，每次问你其中的一些矩形的面积并。

题解：

矩形切割

矩形切割裸题。。。当然也可以用线段树（大坑。。。）

直接挂个模版就过了。

看到Discuss中有人说矩形切割会TLE。可能是常数太大了吧。但我没有TLE呀，而且貌似跑的飞快（时间好像排32名，内存也很小。。。）

#include<bits/stdc++.h>
using namespace std;
struct node
{
    int X1,Y1,X2,Y2;
}R[26];
int s1,cc[26],ans[26];
int read()
{
    int s=0,fh=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')fh=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){s=s*10+(ch-'0');ch=getchar();}
    return s*fh;
}
void Cover(int X1,int Y1,int X2,int Y2,int k,int k1)
{
    while(k<=s1&&(X1>=R[cc[k]].X2||X2<=R[cc[k]].X1||Y1>=R[cc[k]].Y2||Y2<=R[cc[k]].Y1))k++;
    if(k>=s1+1){ans[k1]+=(X2-X1)*(Y2-Y1);return;}
    if(X1<R[cc[k]].X1){Cover(X1,Y1,R[cc[k]].X1,Y2,k+1,k1);X1=R[cc[k]].X1;}
    if(X2>R[cc[k]].X2){Cover(R[cc[k]].X2,Y1,X2,Y2,k+1,k1);X2=R[cc[k]].X2;}
    if(Y1<R[cc[k]].Y1){Cover(X1,Y1,X2,R[cc[k]].Y1,k+1,k1);Y1=R[cc[k]].Y1;}
    if(Y2>R[cc[k]].Y2){Cover(X1,R[cc[k]].Y2,X2,Y2,k+1,k1);Y2=R[cc[k]].Y2;}
}
int main()
{
    int n,m,i,case1=0,C=0,j,sum;
    while(1)
    {
        n=read();m=read();if(n==0&&m==0)break;
        for(i=1;i<=n;i++){R[i].X1=read();R[i].Y1=read();R[i].X2=read();R[i].Y2=read();}
        printf("Case %d:
",++case1);
        C=0;
        for(i=1;i<=m;i++)
        {
            s1=read();
            for(j=1;j<=s1;j++)cc[j]=read();
            for(j=s1;j>=1;j--)Cover(R[cc[j]].X1,R[cc[j]].Y1,R[cc[j]].X2,R[cc[j]].Y2,j+1,j);//矩形切割法
            sum=0;
            for(j=1;j<=s1;j++){sum+=ans[j];ans[j]=0;}
            printf("Query %d: %d
",++C,sum);
        }
        printf("
");
    }
    fclose(stdin);
    fclose(stdout);
    return 0;
}