add links to video lectures

1 files changed, 9 insertions, 4 deletions

diff --git a/README.md b/README.md
index 531d7ea..6c65d2e 100644
--- a/README.md
+++ b/README.md
@@ -151,9 +151,9 @@ And then, we will study methods for solving recurrences,
 which are useful for describing the running times of recursive algorithms.
 One of them, the "master method", is particularly powerful.
 
-For supplemental material, I recommend that you watch this video: 
+For supplemental material, I recommend that you watch this video:
 
-* [ ] http://freevideolectures.com/Course/1941/Introduction-to-Algorithms/3
+* [X] http://freevideolectures.com/Course/1941/Introduction-to-Algorithms/3
 
 This unit will introduce
 
@@ -174,6 +174,7 @@ When you have completed this objective, you should be able to
 #### Required Activities
 
 * [ ] Watch the video, Algorithms Lecture 13: Maximum Sub-array Problem using Divide-and-Conquer, on YouTube.
+  * https://www.youtube.com/watch?v=yBCzO0FpsVc
 * [ ] Study Section 4.1 of the textbook.
 * [ ] Do Exercise 4.1-2 from the textbook as part of Assignment 1. 
 
@@ -188,7 +189,8 @@ When you have completed this objective, you should be able to
 
 #### Required Activities
 
-* [ ] Watch the video, Strassen’s Matrix Multiplication by Divide and Conquer, on YouTube.
+* [ ] Watch the video, Strassen’s Matrix Multiplication by Divide and Conquer, on YouTube. 
+  * https://www.youtube.com/watch?v=1AIvlizGo7Y
 * [ ] Study Section 4.2 of the textbook.
 * [ ] Do Exercise 4.2-1 from the textbook as part of Assignment 1. 
 
@@ -203,7 +205,8 @@ When you have completed this objective, you should be able to
 
 #### Required Activities
 
-* [ ] Watch the video, Lecture 2: Asymptotic Notation | Recurrences | Substitution, Master Method (the Substitution part), at Free Video Lectures.
+* [ ] Watch the video, Lecture 2: Asymptotic Notation | Recurrences | Substitution, Master Method (the Substitution part) 
+  * https://freevideolectures.com/course/1941/introduction-to-algorithms/2
 * [ ] Study Section 4.3 of the textbook.
 * [ ] Do Exercises 4.3-2 from the textbook as part of Assignment 1. 
 
@@ -216,6 +219,7 @@ When you have completed this objective, you should be able to
 #### Required Activities
 
 * [ ] Watch the video, Lecture 2: Asymptotic Notation | Recurrences | Substitution, Master Method (the Recursion part), at Free Video Lectures.
+  * https://freevideolectures.com/course/1941/introduction-to-algorithms/2
 * [ ] Study Section 4.4 of the textbook.
 * [ ] Do Exercise 4.4-7 from the textbook as part of Assignment 1.
 
@@ -228,6 +232,7 @@ When you have completed this objective, you should be able to
 #### Required Activities
 
 * [ ] Watch the video, Lecture 2: Asymptotic Notation | Recurrences | Substitution, Master Method (the Master Method part), at Free Video Lectures.
+  * https://freevideolectures.com/course/1941/introduction-to-algorithms/2
 * [ ] Study Section 4.5 of the textbook.
 * [ ] Do Exercise 4.5-3 from the textbook as part of Assignment 1.