Insertion Sort and Merge Sort

INSERTION-SORT(A)
1 for j ← 2 to length[A]
2     do key ← A[j]
3 //Insert A[j] into the sorted sequence A[1..j - 1].
4          i ← j - 1
5         while i > 0 and A[i] > key
6               do A[i + 1] ← A[i]
7                     i ← i - 1
8         A[i + 1] ← key

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MERGE(A, p, q, r)
1 n1 ← q - p + 1
2 n2 ← r - q
3 //create arrays L[1..n1 + 1] and R[1..n2 + 1]
4 for i ← 1 to n1
5     do L[i] ← A[p + i - 1]
6 for j ← 1 to n2
7     do R[j] ← A[q + j]
8 L[n1 + 1] ← ∞
9 R[n2 + 1] ← ∞
10 i ← 1
11 j ← 1
12 for k ← p to r
13     do if L[i] ≤ R[j]
14     then A[k] ← L[i]
15              i ← i + 1
16     else A[k] ← R[j]
17              j ← j + 1

MERGE-SORT(A, p, r)
1 if p < r
2     then q ← ⌊(p + r)/2⌋
3             MERGE-SORT(A, p, q)
4             MERGE-SORT(A, q + 1, r)
5             MERGE(A, p, q, r)