From aaddcfed0e799443aeb60cb480d4a89a7379d647 Mon Sep 17 00:00:00 2001
From: vrundajasani <vrundajsani@gmail.com>
Date: Tue, 3 May 2022 16:46:54 -0400
Subject: [PATCH 1/3] Merge sort Algorithm in python
---
projects/Merge_Sort_Algorithm/merge.py | 31 ++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
create mode 100644 projects/Merge_Sort_Algorithm/merge.py
diff --git a/projects/Merge_Sort_Algorithm/merge.py b/projects/Merge_Sort_Algorithm/merge.py
new file mode 100644
index 000000000..5edfe9a4e
--- /dev/null
+++ b/projects/Merge_Sort_Algorithm/merge.py
@@ -0,0 +1,31 @@
+def merge(listA, listB):
+ newlist = list()
+ a = 0
+ b = 0
+ while a < len(listA) and b < len(listB):
+ if listA[a] < listB[b]:
+ newlist.append(listA[a])
+ a += 1
+ else:
+ newlist.append(listB[b])
+ b += 1
+ while a < len(listA):
+ newlist.append(listA[a])
+ a += 1
+ while b < len(listB):
+ newlist.append(listB[b])
+ b += 1
+ return newlist
+
+def merge_sort(input_list):
+ if len(input_list) <= 1:
+ return input_list
+ else:
+ mid = len(input_list) // 2
+ left = merge_sort(input_list[:mid])
+ right = merge_sort(input_list[mid:])
+ newlist = merge(left, right)
+ return newlist
+
+a = [56, 89, 45, 34, 90, 32, 20, 67, 43]
+print(merge_sort(a))
\ No newline at end of file
From 53c11be426fd1cc8018a1dff044ed28eb6a149e5 Mon Sep 17 00:00:00 2001
From: vrundajasani <vrundajsani@gmail.com>
Date: Tue, 3 May 2022 16:57:12 -0400
Subject: [PATCH 2/3] Added comments to code
---
projects/Merge_Sort_Algorithm/merge.py | 104 ++++++++++++++++++-------
1 file changed, 75 insertions(+), 29 deletions(-)
diff --git a/projects/Merge_Sort_Algorithm/merge.py b/projects/Merge_Sort_Algorithm/merge.py
index 5edfe9a4e..5a3319e7d 100644
--- a/projects/Merge_Sort_Algorithm/merge.py
+++ b/projects/Merge_Sort_Algorithm/merge.py
@@ -1,31 +1,77 @@
-def merge(listA, listB):
- newlist = list()
- a = 0
- b = 0
- while a < len(listA) and b < len(listB):
- if listA[a] < listB[b]:
- newlist.append(listA[a])
- a += 1
- else:
- newlist.append(listB[b])
- b += 1
- while a < len(listA):
- newlist.append(listA[a])
- a += 1
- while b < len(listB):
- newlist.append(listB[b])
- b += 1
- return newlist
+# Python program for implementation of MergeSort
+
+# Merges two subarrays of arr[].
+# First subarray is arr[l..m]
+# Second subarray is arr[m+1..r]
+
+
+def merge(arr, l, m, r):
+ n1 = m - l + 1
+ n2 = r - m
+
+ # create temp arrays
+ L = [0] * (n1)
+ R = [0] * (n2)
+
+ # Copy data to temp arrays L[] and R[]
+ for i in range(0, n1):
+ L[i] = arr[l + i]
+
+ for j in range(0, n2):
+ R[j] = arr[m + 1 + j]
+
+ # Merge the temp arrays back into arr[l..r]
+ i = 0 # Initial index of first subarray
+ j = 0 # Initial index of second subarray
+ k = l # Initial index of merged subarray
-def merge_sort(input_list):
- if len(input_list) <= 1:
- return input_list
- else:
- mid = len(input_list) // 2
- left = merge_sort(input_list[:mid])
- right = merge_sort(input_list[mid:])
- newlist = merge(left, right)
- return newlist
+ while i < n1 and j < n2:
+ if L[i] <= R[j]:
+ arr[k] = L[i]
+ i += 1
+ else:
+ arr[k] = R[j]
+ j += 1
+ k += 1
+
+ # Copy the remaining elements of L[], if there
+ # are any
+ while i < n1:
+ arr[k] = L[i]
+ i += 1
+ k += 1
+
+ # Copy the remaining elements of R[], if there
+ # are any
+ while j < n2:
+ arr[k] = R[j]
+ j += 1
+ k += 1
+
+# l is for left index and r is right index of the
+# sub-array of arr to be sorted
-a = [56, 89, 45, 34, 90, 32, 20, 67, 43]
-print(merge_sort(a))
\ No newline at end of file
+def mergeSort(arr, l, r):
+ if l < r:
+
+ # Same as (l+r)//2, but avoids overflow for
+ # large l and h
+ m = l+(r-l)//2
+
+ # Sort first and second halves
+ mergeSort(arr, l, m)
+ mergeSort(arr, m+1, r)
+ merge(arr, l, m, r)
+
+
+# Driver code to test above
+arr = [100, 50, 80, 25, 20, 5]
+n = len(arr)
+print("Given array is")
+for i in range(n):
+ print("%d" % arr[i],end=" ")
+
+mergeSort(arr, 0, n-1)
+print("\n\nSorted array is")
+for i in range(n):
+ print("%d" % arr[i],end=" ")
\ No newline at end of file
From df9124ab45b3fa01795c9e721d251d2c34eeb7a9 Mon Sep 17 00:00:00 2001
From: Vrunda Jasani <98854578+vrundajasani@users.noreply.github.com>
Date: Wed, 4 May 2022 16:35:36 -0400
Subject: [PATCH 3/3] Create README.md
---
projects/Merge_Sort_Algorithm/README.md | 31 +++++++++++++++++++++++++
1 file changed, 31 insertions(+)
create mode 100644 projects/Merge_Sort_Algorithm/README.md
diff --git a/projects/Merge_Sort_Algorithm/README.md b/projects/Merge_Sort_Algorithm/README.md
new file mode 100644
index 000000000..be3b0dd8b
--- /dev/null
+++ b/projects/Merge_Sort_Algorithm/README.md
@@ -0,0 +1,31 @@
+## Merge Sort Algorithm
+
+This script sorts the given array using merge sort algorithm. You can change the predefined "arr" to sort your array.
+
+### Prerequisites
+
+You only need python to run this script. You can visit [here](https://www.python.org/downloads/) to download python.
+
+### How to run the script
+
+Running the script is really simple! Just open a terminal in the folder where your script is located and run the following command :
+
+```
+python3 merge.py
+```
+
+### Sample use of the script
+
+```
+python3 merge.py
+
+ Given array is
+ 100 50 80 20 70
+
+ Sorted array is
+ 20 50 70 80 100
+
+```
+### Author Name
+
+Vrunda Jasani