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import java.io.*;
import java.util.*;
public class billboard {
public static void main(String[] args) throws IOException {
// initialize file I/O
BufferedReader br = new BufferedReader(new FileReader("billboard.in"));
PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter("billboard.out")));
// read in the locations of the first billboard
StringTokenizer st = new StringTokenizer(br.readLine());
int x1 = Integer.parseInt(st.nextToken());
int y1 = Integer.parseInt(st.nextToken());
int x2 = Integer.parseInt(st.nextToken());
int y2 = Integer.parseInt(st.nextToken());
// read in the locations of the second billboard
st = new StringTokenizer(br.readLine());
int x3 = Integer.parseInt(st.nextToken());
int y3 = Integer.parseInt(st.nextToken());
int x4 = Integer.parseInt(st.nextToken());
int y4 = Integer.parseInt(st.nextToken());
// read in the locations of the truck
st = new StringTokenizer(br.readLine());
int x5 = Integer.parseInt(st.nextToken());
int y5 = Integer.parseInt(st.nextToken());
int x6 = Integer.parseInt(st.nextToken());
int y6 = Integer.parseInt(st.nextToken());
br.close();
// the visible area is the sum of the visible area of the first billboard and the second billboard
int combinedArea = visibleArea(x1, y1, x2, y2, x5, y5, x6, y6) + visibleArea(x3, y3, x4, y4, x5, y5, x6, y6);
// print the answer
pw.println(combinedArea);
pw.close();
}
/**
* Given the lower-left and upper-right corners of a rectangle, return the area of the rectangle
* @param x1 x-coordinate of lower-left corner
* @param y1 y-coordinate of lower-left corner
* @param x2 x-coordinate of upper-right corner
* @param y2 y-coordinate of upper-right corner
* @return area of the rectangle
*/
public static int areaOfRectangle(int x1, int y1, int x2, int y2) {
return (x2-x1)*(y2-y1);
}
/**
* Given the corners of two rectangles, return the area inside the first rectangle
* but outside the second
* @param x1 x-coordinate of lower-left corner of first rectangle
* @param y1 y-coordinate of lower-left corner of first rectangle
* @param x2 x-coordinate of upper-right corner of first rectangle
* @param y2 y-coordinate of upper-right corner of first rectangle
* @param x3 x-coordinate of lower-left corner of second rectangle
* @param y3 y-coordinate of upper-right corner of second rectangle
* @param x4 x-coordinate of lower-left corner of second rectangle
* @param y4 y-coordinate of upper-right corner of second rectangle
* @return
*/
public static int visibleArea(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4) {
// start by computing the area that would be visible if there were no second rectangle
int visibleArea = areaOfRectangle(x1, y1, x2, y2);
// compute the boundaries of the intersection
int leftmostBlockedX = Math.max(x1, x3);
int rightmostBlockedX = Math.min(x2, x4);
int bottommostBlockedY = Math.max(y1, y3);
int topmostBlockedY = Math.min(y2, y4);
// if the second rectangle does exist, subtract out the area that it blocks
if(leftmostBlockedX < rightmostBlockedX && bottommostBlockedY < topmostBlockedY) {
visibleArea -= areaOfRectangle(leftmostBlockedX, bottommostBlockedY, rightmostBlockedX, topmostBlockedY);
}
return visibleArea;
}
}
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