题目

Find the total area covered by two rectilinear rectangles in a2D 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.

解题之法

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

分析

们只要算出长和宽，即可求出交集区域的大小，然后从两个巨型面积之和中减去交集面积就是最终答案。
求交集区域的长和宽也不难，由于交集都是在中间，所以横边的左端点是两个矩形左顶点横坐标的较大值，右端点是两个矩形右顶点的较小值，同理，竖边的下端点是两个矩形下顶点纵坐标的较大值，上端点是两个矩形上顶点纵坐标的较小值。