Merge pull request #1379 from cp-algorithms/remove-missing-links

Kostero · web-flow · commit 7a9c1c95ee9e · 2024-10-22T23:04:20.000-04:00
Remove broken links #1137
diff --git a/src/combinatorics/binomial-coefficients.md b/src/combinatorics/binomial-coefficients.md
@@ -220,15 +220,13 @@ When $m$ is not square-free, a [generalization of Lucas's theorem for prime powe
 * [LightOj - Necklaces](http://www.lightoj.com/volume_showproblem.php?problem=1419)
 * [HACKEREARTH: Binomial Coefficient](https://www.hackerearth.com/problem/algorithm/binomial-coefficient-1/description/)
 * [SPOJ - Ada and Teams](http://www.spoj.com/problems/ADATEAMS/)
-* [DevSkill - Drive In Grid](https://devskill.com/CodingProblems/ViewProblem/61)
 * [SPOJ - Greedy Walking](http://www.spoj.com/problems/UCV2013E/)
 * [UVa 13214 - The Robot's Grid](https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=5137)
 * [SPOJ - Good Predictions](http://www.spoj.com/problems/GOODB/)
 * [SPOJ - Card Game](http://www.spoj.com/problems/HC12/)
 * [SPOJ - Topper Rama Rao](http://www.spoj.com/problems/HLP_RAMS/)
 * [UVa 13184 - Counting Edges and Graphs](https://uva.onlinejudge.org/index.php?option=onlinejudge&page=show_problem&problem=5095)
 * [Codeforces - Anton and School 2](http://codeforces.com/contest/785/problem/D)
-* [DevSkill - Parandthesis](https://devskill.com/CodingProblems/ViewProblem/255)
 * [Codeforces - Bacterial Melee](http://codeforces.com/contest/760/problem/F)
 * [Codeforces - Points, Lines and Ready-made Titles](http://codeforces.com/contest/872/problem/E)
 * [SPOJ - The Ultimate Riddle](https://www.spoj.com/problems/DCEPC13D/)
diff --git a/src/combinatorics/inclusion-exclusion.md b/src/combinatorics/inclusion-exclusion.md
@@ -449,7 +449,6 @@ A list of tasks that can be solved using the principle of inclusions-exclusions:
 * [TopCoder SRM 390 "SetOfPatterns" [difficulty: medium]](http://www.topcoder.com/stat?c=problem_statement&pm=8307)
 * [TopCoder SRM 176 "Deranged" [difficulty: medium]](http://community.topcoder.com/stat?c=problem_statement&pm=2013)
 * [TopCoder SRM 457 "TheHexagonsDivOne" [difficulty: medium]](http://community.topcoder.com/stat?c=problem_statement&pm=10702&rd=14144&rm=303184&cr=22697599)
-* [Test>>>thebest "HarmonicTriples" (in Russian) [difficulty: medium]](http://esci.ru/ttb/statement-62.htm)
 * [SPOJ #4191 MSKYCODE "Sky Code" [difficulty: medium]](http://www.spoj.com/problems/MSKYCODE/)
 * [SPOJ #4168 SQFREE "Square-free integers" [difficulty: medium]](http://www.spoj.com/problems/SQFREE/)
 * [CodeChef "Count Relations" [difficulty: medium]](http://www.codechef.com/JAN11/problems/COUNTREL/)
diff --git a/src/geometry/planar.md b/src/geometry/planar.md
@@ -13,7 +13,7 @@ In this article we will deal with finding both inner and outer faces of a planar
 
 ## Some facts about planar graphs
 
-In this section we present several facts about planar graphs without proof. Readers who are interested in proofs should refer to [Graph Theory by R. Diestel](https://diestel-graph-theory.com/) (see [video lectures](https://www.youtube.com/@DiestelGraphTheory) based on this book) or some other book.
+In this section we present several facts about planar graphs without proof. Readers who are interested in proofs should refer to [Graph Theory by R. Diestel](https://www.math.uni-hamburg.de/home/diestel/books/graph.theory/preview/Ch4.pdf) (see also [video lectures on planarity](https://www.youtube.com/@DiestelGraphTheory) based on this book) or some other book.
 
 ### Euler's theorem
 Euler's theorem states that any correct embedding of a connected planar graph with $n$ vertices, $m$ edges and $f$ faces satisfies:
diff --git a/src/graph/strongly-connected-components.md b/src/graph/strongly-connected-components.md
@@ -152,7 +152,6 @@ Our condensation graph is now given by the vertices `components` (one strongly c
 * [SPOJ - Good Travels](http://www.spoj.com/problems/GOODA/)
 * [SPOJ - Lego](http://www.spoj.com/problems/LEGO/)
 * [Codechef - Chef and Round Run](https://www.codechef.com/AUG16/problems/CHEFRRUN)
-* [Dev Skills - A Song of Fire and Ice](https://devskill.com/CodingProblems/ViewProblem/79)
 * [UVA - 11838 - Come and Go](https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=2938)
 * [UVA 247 - Calling Circles](https://uva.onlinejudge.org/index.php?option=onlinejudge&page=show_problem&problem=183)
 * [UVA 13057 - Prove Them All](https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=4955)
