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.

Example:

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

思路：两个面积之和，等于两个面积减去公共的overlap面积；

求公共的面积，等于 右边一维的最小值，减去左边一维的最大值；同理求得 y轴的length；两者相乘就是overlap的面积；

class Solution {
    public int computeArea(int A, int B, int C, int D, int E, int F, int G, int H) {
        int abcd = (C - A) * (D - B);
        int efgh = (G - E) * (H - F);
        
        int overlap = getOverlapLength(A, C, E, G) * getOverlapLength(B, D, F, H);
        return abcd + efgh - overlap;
    }
    
    private int getOverlapLength(int A, int C, int E, int G) {
        if(E > C || G < A) {
            return 0;
        }
        return Math.min(C, G) - Math.max(A, E);
    }
}