Python single liner (Geometric Observation)
Geometric ObservationConsidering the rectangle 2 as the reference point.
Now if rectangle 1 is either in the left or right of rectangle 2 they are not intersect
# Geometric Observation
Considering the rectangle 2 as the reference point.
Now if rectangle 1 is either in the left or right of rectangle 2 they are not intersecting.
Also if rectange 1 is either above or below the rectangle 2 they are not intersecting in that case either.
Only 1 of the 4 conditions is enough to prove that rectangles are not intersecting.

# Code
```python3 []
class Solution:
    def isRectangleOverlap(self, rec1: List[int], rec2: List[int]) -> bool:

        x1, y1, x2, y2 = rec1
        x3, y3, x4, y4 = rec2
        
        return not (x3 >= x2 or x1 >= x4 or y1 >= y4 or y3 >= y2)
            
```
['Python3']