replace restricted link

diff --git a/docs/math/poly/inv.md b/docs/math/poly/inv.md
index 344e913..f19b02f 100644 (file)
--- a/docs/math/poly/inv.md
+++ b/docs/math/poly/inv.md
@@ -71,4 +71,4 @@ $$T\left(n\right)=T\left(\frac{n}{2}\right)+O\left(n\log{n}\right)=O\left(n\log{
 
 ## Examples
 
-1. 有标号简单无向连通图计数：「BZOJ 3456」城市规划
+1. 有标号简单无向连通图计数：[「poj 1737」Connected Graph](http://poj.org/problem?id=1737)