merge sort python added

Sorting/Merge Sort/Python/MergeSort.py

@@ -0,0 +1,68 @@
+# merge sort in python
+
+#first array l to m
+#second array m+1 to r
+def merge(arr, l, m, r):
+    n1 = m-l+1
+    n2 = r-m
+
+    #temp arrays
+    L = [0] * (n1)
+    R = [0] * (n2)
+
+    for i in range(0, n1):
+        L[i] = arr[l+i]
+
+    for j in range(0, n2):
+        R[j] = arr[m+1+j]
+
+    i=0
+    j=0
+    k=l
+
+    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
+
+
+    while i<n1:
+        arr[k] = L[i]
+        i+=1
+        k+=1
+
+    while j<n1:
+        arr[k] = R[j]
+        j+=1
+        k+=1
+
+
+def mergeSort(arr, l, r):
+    if l<r:
+        m = (l+(r-1))/2
+        mergeSort(arr, l, m)
+        mergeSort(arr, m+1, r)
+        merge(arr, l, m, r)
+
+
+# test code
+
+arr = [12, 11, 13, 5, 6, 7]
+n = len(arr)
+mergeSort(arr, 0, n-1)
+for i in range(n):
+    print(arr[i])
+
+
+
+
+
+
+
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+