LeetCode-Rectangle Area

Find the total area covered by two rectilinear rectangles in a 2D plane.

Each rectangle is defined by its bottom left corner and top right corner as shown in the figure.

Assume that the total area is never beyond the maximum possible value of int.

Credits:
Special thanks to @mithmatt for adding this problem, creating the above image and all test cases.

 

 Analysis:

Area = area1 + area2 - overlap. To find out overlapped area, we decompose the matrix into x dimension and y dimension; we then find out the overlapped interval in x&y diemension respectively, which are the four lines constructing the overlapped rectangle.

 

Solution:

public class Solution {
    public int computeArea(int A, int B, int C, int D, int E, int F, int G, int H) {
        int area1 = (C-A) * (D-B);
        int area2 = (G-E) * (H-F);
        int overlap = 0;
        
        if (E<C && A<G && F<D && B<H){
            int left = Math.max(A,E);
            int right = Math.min(C,G);
            int up = Math.min(D,H);
            int bottom = Math.max(B,F);
            overlap = (right-left) * (up-bottom);
        }
        return area1+area2-overlap;
    }
}