diff --git a/copypasta/monotone_stack.go b/copypasta/monotone_stack.go
index d4bd9cb59a..5cbc60d53c 100644
--- a/copypasta/monotone_stack.go
+++ b/copypasta/monotone_stack.go
@@ -16,7 +16,7 @@ https://cp-algorithms.com/data_structures/stack_queue_modification.html
       https://www.luogu.com.cn/problem/P2866 http://poj.org/problem?id=3250
       https://leetcode-cn.com/problems/next-greater-element-i/ LC496/周赛18BA
       https://leetcode-cn.com/problems/next-greater-element-ii/ LC503/周赛18BB
-      NEERC05 https://onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=825&page=show_problem&problem=4494
+      NEERC05，UVa 1619 https://onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=825&page=show_problem&problem=4494
 柱状图中最大的矩形 LC84 https://leetcode-cn.com/problems/largest-rectangle-in-histogram/ http://poj.org/problem?id=2559 http://poj.org/problem?id=2082
 最大全 1 矩形 LC85（实现见下面的 maximalRectangleArea）https://leetcode-cn.com/problems/maximal-rectangle/
 接雨水 LC42 https://leetcode-cn.com/problems/trapping-rain-water/
diff --git a/copypasta/rand.go b/copypasta/rand.go
index 6e6470f750..90ababa499 100644
--- a/copypasta/rand.go
+++ b/copypasta/rand.go
@@ -27,7 +27,7 @@ https://www.cnblogs.com/ECJTUACM-873284962/p/8468831.html
 Heuristic algorithm for Hamiltonian path in undirected graphs https://codeforces.com/blog/entry/90743
 
 模板题 https://www.luogu.com.cn/problem/P1337
-LC1515/周赛197D https://leetcode-cn.com/contest/weekly-contest-197/problems/best-position-for-a-service-centre/ http://poj.org/problem?id=2420 https://onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=14&page=show_problem&problem=1169
+LC1515/周赛197D https://leetcode-cn.com/contest/weekly-contest-197/problems/best-position-for-a-service-centre/ http://poj.org/problem?id=2420 UVa 10228 https://onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=14&page=show_problem&problem=1169
 todo 教学题 https://atcoder.jp/contests/intro-heuristics/tasks/intro_heuristics_a
  https://atcoder.jp/contests/ahc001/tasks/ahc001_a
  https://atcoder.jp/contests/ahc002/tasks/ahc002_a
diff --git a/copypasta/sort.go b/copypasta/sort.go
index 604e9e7514..05727e65dd 100644
--- a/copypasta/sort.go
+++ b/copypasta/sort.go
@@ -356,7 +356,7 @@ func sortCollections() {
 	//       https://www.luogu.com.cn/problem/P1570
 	//       https://loj.ac/p/149
 	// 连续子段的算数平均值 https://codeforces.com/edu/course/2/lesson/6/4/practice/contest/285069/problem/A https://codeforces.com/problemset/problem/1003/C https://www.luogu.com.cn/problem/P1404 https://www.acwing.com/problem/content/104/
-	//     O(n) 做法见 04 年集训队周源论文《浅谈数形结合思想在信息学竞赛中的应用》（或紫书 p.243 例题 8-9 https://onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=447&page=show_problem&problem=4197）
+	//     O(n) 做法见 04 年集训队周源论文《浅谈数形结合思想在信息学竞赛中的应用》（或紫书 p.243 例题 8-9，UVa 1451 https://onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=447&page=show_problem&problem=4197）
 	// 与 0-1 背包结合，即最优比率背包 https://www.luogu.com.cn/problem/P4377 https://ac.nowcoder.com/acm/contest/2271/F
 	// 与生成树结合，即最优比率生成树 https://www.luogu.com.cn/problem/P4951 http://poj.org/problem?id=2728
 	// 与负环判定结合，即最优比率环 https://www.luogu.com.cn/problem/P1768 https://www.luogu.com.cn/problem/P2868 https://www.luogu.com.cn/problem/P3199 http://poj.org/problem?id=3621