Given N axis-aligned rectangles where N > 0, determine if they all together form an exact cover of a rectangular region.
Each rectangle is represented as a bottom-left point and a top-right point. For example, a unit square is represented as [1,1,2,2]. (coordinate of bottom-left point is (1, 1) and top-right point is (2, 2)).
Example 1:
rectangles = [
[1,1,3,3],
[3,1,4,2],
[3,2,4,4],
[1,3,2,4],
[2,3,3,4]
]
Return true. All 5 rectangles together form an exact cover of a rectangular region.
Example 2:
rectangles = [
[1,1,2,3],
[1,3,2,4],
[3,1,4,2],
[3,2,4,4]
]
Return false. Because there is a gap between the two rectangular regions.
Example 3:
rectangles = [
[1,1,3,3],
[3,1,4,2],
[1,3,2,4],
[3,2,4,4]
]
Return false. Because there is a gap in the top center.
Example 4:
rectangles = [
[1,1,3,3],
[3,1,4,2],
[1,3,2,4],
[2,2,4,4]
]
Return false. Because two of the rectangles overlap with each other.
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