223. Rectangle Area

题目

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.

Example:

Input: A = -3, B = 0, C = 3, D = 4, E = 0, F = -1, G = 9, H = 2
Output: 45

Note:

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

题目大意

在二维平面上计算出两个由直线构成的矩形重叠后形成的总面积。每个矩形由其左下顶点和右上顶点坐标表示，如图所示。说明: 假设矩形面积不会超出 int 的范围。

解题思路

• 给出两个矩形的坐标，求这两个矩形在坐标轴上覆盖的总面积。
• 几何题，由于只有 2 个矩形，所以按照题意做即可。先分别求两个矩形的面积，加起来再减去两个矩形重叠的面积。

代码

package leetcode

func computeArea(A int, B int, C int, D int, E int, F int, G int, H int) int {
	X0, Y0, X1, Y1 := max(A, E), max(B, F), min(C, G), min(D, H)
	return area(A, B, C, D) + area(E, F, G, H) - area(X0, Y0, X1, Y1)
}

func area(x0, y0, x1, y1 int) int {
	l, h := x1-x0, y1-y0
	if l <= 0 || h <= 0 {
		return 0
	}
	return l * h
}