LeetCode - Rectangle Overlap

A rectangle is represented as a list [x1, y1, x2, y2], where (x1, y1) are the coordinates of its bottom-left corner, and (x2, y2) are the coordinates of its top-right corner.

Two rectangles overlap if the area of their intersection is positive.  To be clear, two rectangles that only touch at the corner or edges do not overlap.

Given two (axis-aligned) rectangles, return whether they overlap.

Example 1:

Input: rec1 = [0,0,2,2], rec2 = [1,1,3,3]
Output: true
Example 2:

Input: rec1 = [0,0,1,1], rec2 = [1,0,2,1]
Output: false
Notes:

Both rectangles rec1 and rec2 are lists of 4 integers.
All coordinates in rectangles will be between -10^9 and 10^9.

　　分情况讨论， 讨论不可能相交的四种情况（横轴与横轴比较，纵轴与纵轴比较）

class Solution {
    public boolean isRectangleOverlap(int[] rec1, int[] rec2) {
        //bottom-left corner
        int x1r1 = rec1[0];
        int y1r1 = rec1[1];
        //top-right corner
        int x2r1 = rec1[2];
        int y2r1 = rec1[3];

        //bottom-left corner
        int x1r2 = rec2[0];
        int y1r2 = rec2[1];
        //top-right corner
        int x2r2 = rec2[2];
        int y2r2 = rec2[3];

        if(y2r1 <= y1r2 || y2r2 <= y1r1){
            return false;
        }
        if(x2r2 <= x1r1 || x2r1 <= x1r2){
            return false;
        }
        return true;
    }
}