Added the Jarvis march in Coconut (#734)

Author: Amaras

contents/jarvis_march/code/coconut/jarvis_march.coco

@@ -0,0 +1,40 @@
+data point(x=0, y=0):
+    def __str__(self):
+        return f'({self.x}, {self.y})'
+
+# Is the turn counter-clockwise?
+def counter_clockwise(p1 is point, p2 is point, p3 is point) =
+    (p3.y - p1.y) * (p2.x - p1.x) >= (p2.y - p1.y) * (p3.x - p1.x)
+
+
+def jarvis_march(gift: point[]) -> point[]:
+    point_on_hull = min(gift) # The leftmost point in the gift
+    hull = [point_on_hull] # It is guaranteed it will be on the hull.
+
+    while True:
+        # Candidate for the next point in the hull
+        endpoint = gift[0]
+        for p in gift:
+            if (endpoint == point_on_hull
+                or not counter_clockwise(p, hull[-1], endpoint)):
+                endpoint = p
+
+        point_on_hull = endpoint
+
+        # Check if the gift is completely covered.
+        if hull[0] == endpoint:
+            return hull
+        hull.append(point_on_hull)
+
+
+if __name__ == '__main__':
+    test_gift = [
+        (-5, 2), (5, 7), (-6, -12), (-14, -14), (9, 9),
+        (-1, -1), (-10, 11), (-6, 15), (-6, -8), (15, -9),
+        (7, -7), (-2, -9), (6, -5), (0, 14), (2, 8)
+    ] |> map$(t -> point(*t)) |> list
+    hull = jarvis_march(test_gift)
+
+    print("[#] The points in the hull are:")
+    for point in hull:
+        print(point)

contents/jarvis_march/jarvis_march.md

@@ -50,6 +50,8 @@ Since this algorithm, there have been many other algorithms that have advanced t
 [import, lang:"v"](code/v/jarvis.v)
 {% sample lang="rust" %}
 [import, lang:"rust"](code/rust/jarvis_march.rs)
+{% sample lang="coco" %}
+[import, lang:"coconut"](code/coconut/jarvis_march.coco)
 {% endmethod %}
 
 <script>