diff --git a/notes/midterm.md b/notes/midterm.md
new file mode 100644
index 0000000..cc71719
--- /dev/null
+++ b/notes/midterm.md
@@ -0,0 +1,44 @@
+# Alogorithm Midterm Access
+
+## Sorting Problem
+
+Comparison Sorts(Lower bound is $\Omega(n \lg n)$ because decision-tree model)
+
+* Insertion Sort
+* Selection Sort
+* Merge Sort
+* Quick Sort
+* Heap Sort
+
+Sorting In Linear Time
+
+* Counting Sort
+* Radix Sort
+
+## Asymtotic Notation
+
+* $Theta$-notation
+* $O$-notation
+* $\Omega$-notation
+
+Transitivity, Reflexivity, Symmetry, Transpose Symmetry
+
+Three methods for solving recurrences:
+1. Substitution method
+2. Recursion-tree method
+3. Master method
+
+**Getting asymtotic notation by recursion tree is important**
+
+## Dynamic Programming
+
+* Assembly-line scheduling
+* Rod cutting
+* Longest-Common Subsequence
+* Matrix-chain Multiplication
+
+## Greedy Algorithm
+
+* An Activity Selection Problem
+* Elements of the greedy strategy
+* Huffman codes
diff --git a/pdf/1.Intro.pdf b/pdf/1.Intro.pdf
new file mode 100644
index 0000000..5e8543d
--- /dev/null
+++ b/pdf/1.Intro.pdf
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:7f9c35ebb579468c5fcd501b64f170c02e4a9d8e2607113508b870ff82d8a6a4
+size 304007
diff --git a/pdf/15.Dynamic Programming.pdf b/pdf/15.Dynamic Programming.pdf
new file mode 100644
index 0000000..c8ae5fa
--- /dev/null
+++ b/pdf/15.Dynamic Programming.pdf	
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:c91f76f1a911d0aaf8cbdd998a62327f321300b2dd31089ede8b0926916ea90b
+size 1753723
diff --git a/pdf/16.Greedy Algorithms.pdf b/pdf/16.Greedy Algorithms.pdf
new file mode 100644
index 0000000..263dd82
--- /dev/null
+++ b/pdf/16.Greedy Algorithms.pdf	
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d4a076cc407b6a001d4d145f07e3fe018f1a546b392b9f543751117e81c9a08d
+size 938932
diff --git a/pdf/2.Getting Started.pdf b/pdf/2.Getting Started.pdf
new file mode 100644
index 0000000..448c299
--- /dev/null
+++ b/pdf/2.Getting Started.pdf	
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:6de11acddad45e7443adce3fda8604a40c3c3ba42d27b2ac040e13a456edfd1b
+size 834450
diff --git a/pdf/3.Growth of Functions.pdf b/pdf/3.Growth of Functions.pdf
new file mode 100644
index 0000000..4bd6618
--- /dev/null
+++ b/pdf/3.Growth of Functions.pdf	
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:5df8fa791b9fda4508b37a51d93c6187750e71a0394a15132a6c8f7fbad2c8ce
+size 622331
diff --git a/pdf/4.Divide-and-Conquer.pdf b/pdf/4.Divide-and-Conquer.pdf
new file mode 100644
index 0000000..7b5336d
--- /dev/null
+++ b/pdf/4.Divide-and-Conquer.pdf
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:c67e3ab968b5ce2579b0374a58d9305f2cc8e4348d35bb6c4b20513e4623aeb7
+size 610631
diff --git a/pdf/6.Heapsort.pdf b/pdf/6.Heapsort.pdf
new file mode 100644
index 0000000..b9c1324
--- /dev/null
+++ b/pdf/6.Heapsort.pdf
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:dfa68cf1607b76b6a390362980f3a0f79aa71b6c109c7fbcbe254f1e7cfb519f
+size 600865
diff --git a/pdf/7.Quicksort.pdf b/pdf/7.Quicksort.pdf
new file mode 100644
index 0000000..43cdaaf
--- /dev/null
+++ b/pdf/7.Quicksort.pdf
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:385d8e114cf7d1e4d2a932bda6ce9ef34e2879425e9bd7752dcf16faaac7e08b
+size 510108
diff --git a/pdf/8.Sorting in Linear Time.pdf b/pdf/8.Sorting in Linear Time.pdf
new file mode 100644
index 0000000..1833e16
--- /dev/null
+++ b/pdf/8.Sorting in Linear Time.pdf	
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d2a499b9b145dada52ff7e103cb451a14d9394ce4bc1bc13a3be10462d40abdf
+size 780557