Ankith,
Seriously delayed by urgent issues, here are the two sets of 1 path solution steps, with the ugly original at the top, both with fill and stroke; in both cases each half is 300pt x 600pt (total width 600pt) and a stroke of 15pt aligned to centre:
1) consists of a closed path with 5 or 6 Anchor Points, the latter when the single path is made with Pathfinder>Unite giving one Anchor Point in the middle of the bottom, and with a horizontal gradient C/K/Y that is sharp with 6 gradient sliders C+C/K+K/Y+Y, the sets C/K and K/Y coinciding, thereby painting the vertical black part in the middle instead of a stroked path; the C/K at 48.75% and the C/K at 51.25%; the fill and stroke are shown together and separately below.
2) consists of an open path with 8 Anchor Points, the single path made with Pathfinder>Unite giving one Anchor Point in the middle of the bottom, with:
2a) A horizontal gradient C/Y that is sharp with 4 gradient sliders C+C/Y+Y, the set C/Y coinciding at 50%, and the actual path, visible by the stroke starting at the middle of the bottom and going clockwise all the way round the outer bounds and then up the middle to end at the very top; the fill and stroke are shown together and separately below.
2) has a much simpler gradient with no need for calculation, and since it is made with Pathfinder>Unite, it can be cut at the Anchor Point in the middle of the bottom thereby opening the path, and then the new vertical segment in the middle is made with the Pen Tool by simply first Clicking the (topmost) end Achor Point at the bottom followed by ClickHolding close to the very top and then holding the Spacebar and snapping to the very top Anchor Point, Smart Guides being your friends.
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