Add PolyCut

brianbbsu · Oct 13, 2023 · 9dfeaab · 9dfeaab
1 parent 3b515b5
commit 9dfeaab
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diff --git a/codebook/8_Geometry/PolyCut.cpp b/codebook/8_Geometry/PolyCut.cpp
@@ -0,0 +1,12 @@
+vector<pdd> cut(vector<pdd> poly, pdd s, pdd e) {
+  vector<pdd> res;
+  for (int i = 0; i < SZ(poly); ++i) {
+    pdd cur = poly[i], prv = i ? poly[i - 1] : poly.back();
+    bool side = ori(s, e, cur) < 0;
+    if (side != (ori(s, e, prv) < 0))
+      res.pb(intersect(s, e, cur, prv));
+    if (side)
+      res.pb(cur);
+  }
+  return res;
+}
diff --git a/codebook/content.tex b/codebook/content.tex
@@ -207,6 +207,8 @@ \subsection{VectorInPoly*} % test by qoj 5479
 \lstinputlisting{8_Geometry/Vector_in_poly.cpp}
 \subsection{PolyUnion*} % test by CF 101673 A
 \lstinputlisting{8_Geometry/PolyUnion.cpp}
+\subsection{PolyCut}
+\lstinputlisting{8_Geometry/PolyCut.cpp}
 \subsection{Polar Angle Sort*} % test by NTUJ 2270
 \lstinputlisting{8_Geometry/Polar_Angle_Sort.cpp}
 \subsection{Half plane intersection*} % test by qoj 2162 (World Finals' problem)