leetcode 223-Rectangle Area

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

思路：需要计算正方形覆盖的面积和，关键在于计算重合区域的面积，采用以下计算方式；

设重合区域的左边为（left, bottom）(right, top)

left = Math.max(A, E);

bottom = Math.max(B, F);

right和top的计算比较复杂，需要考虑两个方形不相交的情况，比如：[(-2,-2)(2,2)],[(3,3)(4,4)]，

right = Math.max(Math.min(C, G), left);

top = Math.max(Math.min(D, H), bottom);

代码如下：

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 (G-E)*(H-F)+(C-A)*(D-B)-(right-left)*(top-bottom);
    }