Given an array rectangles where rectangles[i] = [xi, yi, ai, bi] represents an axis-aligned rectangle. The bottom-left point of the rectangle is (xi, yi) and the top-right point of it is (ai, bi).
Return trueif all the rectangles together form an exact cover of a rectangular region.
Example 1:
**Input:** rectangles = [[1,1,3,3],[3,1,4,2],[3,2,4,4],[1,3,2,4],[2,3,3,4]]
**Output:** true
**Explanation:** All 5 rectangles together form an exact cover of a rectangular region.
Example 2:
**Input:** rectangles = [[1,1,2,3],[1,3,2,4],[3,1,4,2],[3,2,4,4]]
**Output:** false
**Explanation:** Because there is a gap between the two rectangular regions.
Example 3:
**Input:** rectangles = [[1,1,3,3],[3,1,4,2],[1,3,2,4],[3,2,4,4]]
**Output:** false
**Explanation:** Because there is a gap in the top center.
Example 4:
**Input:** rectangles = [[1,1,3,3],[3,1,4,2],[1,3,2,4],[2,2,4,4]]
**Output:** false
**Explanation:** Because two of the rectangles overlap with each other.
