Add note about collinearity to Monotone Chain

ferk6a · ferk6a · commit 1819fca10567 · 2021-10-11T16:22:41.000-03:00
diff --git a/src/geometry/convex-hull.md b/src/geometry/convex-hull.md
@@ -158,6 +158,7 @@ with the line connecting the last point in the lower convex hull and the current
 the previous point once added to the hull.
 
 The final convex hull is obtained from the union of the upper and lower convex hull, forming a clockwise hull, and the implementation is as follows.
+If you need collinear points, you just need to include them in the clockwise/counterclockwise routines, by changing `<` to `<=` and `>` to `>=`.
 
 ### Implementation
 
