created 3 way merge sort using python

algorithms/merge_sort/python/3_way_merge_sort.py

@@ -0,0 +1,91 @@
+def merge(garray, low, mid1, mid2, high, destarray):
+    i = low
+    j = mid1
+    k = mid2
+    l = low
+    while ((i < mid1) and (j < mid2) and (k < high)):
+        if(garray[i] < garray[j]):
+            if(garray[i] < garray[k]):
+                destarray[l] = garray[i]
+                l += 1
+                i += 1
+            else:
+                destarray[l] = garray[k]
+                l += 1
+                k += 1
+        else:
+            if(garray[j] < garray[k]):
+                destarray[l] = garray[j]
+                l += 1
+                j += 1
+            else:
+                destarray[l] = garray[k]
+                l += 1
+                k += 1
+    while ((i < mid1) and (j < mid2)):
+        if(garray[i] < garray[j]):
+            destarray[l] = garray[i]
+            l += 1
+            i += 1
+        else:
+            destarray[l] = garray[j]
+            l += 1
+            j += 1
+    while ((j < mid2) and (k < high)):
+        if(garray[j] < garray[k]):
+            destarray[l] = garray[j]
+            l += 1
+            j += 1
+        else:
+            destarray[l] = garray[k]
+            l += 1
+            k += 1
+    while ((i < mid1) and (k < high)):
+        if(garray[i] < garray[k]):
+            destarray[l] = garray[i]
+            l += 1
+            i += 1
+        else:
+            destarray[l] = garray[k]
+            l += 1
+            k += 1 
+    while (i < mid1):
+        destarray[l] = garray[i]
+        l += 1
+        i += 1
+    while (j < mid2):
+        destarray[l] = garray[j]
+        l += 1
+        j += 1
+    while (k < high):
+        destarray[l] = garray[k]
+        l += 1
+        k += 1
+""" Performin the merge sort algorithm on the 
+given array of values in the rangeof indices 
+[low, high). low is minimum index, high is 
+maximum index (exclusive) """
+def mergeSort3WayRec(gArray, low, high, destArray):
+    if (high - low < 2):
+        return
+    mid1 = low + ((high - low) // 3)
+    mid2 = low + 2 * ((high - low) // 3) + 1
+    mergeSort3WayRec(destArray, low, mid1, gArray)
+    mergeSort3WayRec(destArray, mid1, mid2, gArray)
+    mergeSort3WayRec(destArray, mid2, high, gArray)
+    merge(destArray, low, mid1, mid2, high, gArray)
+def mergeSort3Way(gArray, n):
+    if (n == 0):
+        return 
+    fArray = []
+    fArray = gArray.copy()
+    mergeSort3WayRec(fArray, 0, n, gArray)
+    gArray = fArray.copy()
+    return gArray
+data =[]
+for i in range(10):
+    data.append(int(input()))
+data = mergeSort3Way(data, 10)
+print("After 3 way merge sort: ", end="")
+for i in range(10):
+    print(f"{data[i]} ", end="")