Easy-题目42：223. Rectangle Area

题目原文：
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.
题目大意：
给出(A,B),(C,D),(E,F),(G,H)四个点，如图所示求围成图形的面积。
题目分析：
在纸上多画几种情况可以发现，A>=G、B>=H、C<=E、D<=F这四种情况下，两个矩形是不重叠的，因此直接计算面积之和，否则要减去重叠部分。
源码：（language：cpp）

class Solution {
public:
    int computeArea(int A, int B, int C, int D, int E, int F, int G, int H) {
        int area = (C-A)*(D-B) + (G-E)*(H-F);
        if (A >= G || B >= H || C <= E || D <= F)
           return area;
        int top = min(D, H);
        int bottom = max(B, F);
        int left = max(A, E);
        int right = min(C, G);
        return area - (top-bottom)*(right-left);
    }
};

成绩：
36ms,beats 20.05%，众数36ms,37.38%.