更正url

更正url

算法思维系列/UnionFind算法应用.md

@@ -18,7 +18,7 @@
 
 [130.被围绕的区域](https://leetcode-cn.com/problems/surrounded-regions)
 
-[990.等式方程的可满足性](https://leetcode-cn.com/problems/surrounded-regions)
+[990.等式方程的可满足性](https://leetcode-cn.com/problems/satisfiability-of-equality-equations)
 
 [261.以图判树](https://leetcode-cn.com/problems/graph-valid-tree/)
 
@@ -254,6 +254,8 @@ boolean equationsPossible(String[] equations) {
 
 ======其他语言代码======
 
+### java
+
 第261题的Java代码（提供：[LEODPEN](https://github.com/LEODPEN)）
 
 ```java