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.

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

这道题给出两个矩形的顶点坐标，让求两个矩形覆盖的总面积。

这道题的关键是判断两个矩形有没有重复，有重复需要减去重复的部分的面积，下面的代码提供了一种找有没有重复矩形的方法：

public class Solution {
    public int computeArea(int A, int B, int C, int D, int E, int F, int G, int H) {
        int left = Math.max(A, E); int right = Math.max(Math.min(C, G), left);
        int bottom = Math.max(B, F); int top = Math.max(Math.min(D, H), bottom);
        return (C - A) * (D - B) + (G - E) * (H - F) - (top - bottom) * (right - left);
    }
}