凸包：fix typo

diff --git a/docs/geometry/convex-hull.md b/docs/geometry/convex-hull.md
index a21fde1..f843d41 100644 (file)
--- a/docs/geometry/convex-hull.md
+++ b/docs/geometry/convex-hull.md
@@ -45,7 +45,7 @@ stk[++tp] =
     1;  //栈内添加第一个元素，且不更新used，使得1在最后封闭凸包时也对单调栈更新
 for (int i = 2; i <= n; ++i) {
   while (tp >= 2 && (p[stk[tp]] - p[stk[tp - 1]]) * (p[i] - p[stk[tp]]) <=
-                        1)  //此处*被重载为叉积
+                        0)  //此处*被重载为叉积
     used[stk[tp--]] = 0;
   used[i] = 1;  // used表示在凸壳上
   stk[++tp] = i;