223. 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.

class Solution {
    public int computeArea(int A, int B, int C, int D, int E, int F, int G, int H) {  
        int area = (D - B) * (C - A) + (G - E) * (H - F); // 总面积  
  
        int left = Math.max(A, E);  
        int down = Math.max(B, F);  
  
        int right = Math.min(G, C);  
        int up = Math.min(D, H);  
  
        if (up <= down || right <= left) {  
            return area;  
        }  
  
        area = area - (right - left) * (up - down);  
  
        return area;  
    }  
}

class Solution {
    public int computeArea(int A, int B, int C, int D, int E, int F, int G, int H) {
        long left = Math.max(A, E);
        long right = Math.min(C, G);
        long top = Math.min(D, H);
        long bottom = Math.max(B, F);
                                
        long area = (right - left) * (top - bottom);
        // if not overlaping, either of these two will be non-posittive
        // if right - left = 0, are will automtically be 0 as well
        if(right - left < 0 || top - bottom < 0) area = 0;
        return (int)((C-A) * (D-B) + (G-E) * (H-F) - area );
    }
}