Handle the degenerate case of two identical points.

AbdeltwabMF · adamant-pwn · commit c3250a25bc42 · 2024-02-24T19:25:00.000+01:00
This fix addresses the situation where the convex hull consists
of two identical points and the hull is strictly convex
(i.e., collinear points are not included).
diff --git a/src/geometry/convex-hull.md b/src/geometry/convex-hull.md
@@ -86,6 +86,9 @@ void convex_hull(vector<pt>& a, bool include_collinear = false) {
         st.push_back(a[i]);
     }
 
+    if (include_collinear == false && st.size() == 2 && st[0] == st[1])
+        st.pop_back();
+
     a = st;
 }
 ```

Original file line number	Diff line number	Diff line change
`@@ -86,6 +86,9 @@ void convex_hull(vector<pt>& a, bool include_collinear = false) {`
`86`	`86`	`st.push_back(a[i]);`
`87`	`87`	`}`
`88`	`88`
	`89`	`+ if (include_collinear == false && st.size() == 2 && st[0] == st[1])`
	`90`	`+ st.pop_back();`
	`91`	`+`
`89`	`92`	`a = st;`
`90`	`93`	`}`
`91`	`94`	```