Merge_Sort_algo.py

Python/Merge_Sort_algo.py

@@ -0,0 +1,74 @@
+# 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 
+
+    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 
+def mergeSort(arr,l,r): 
+    if l < r: 
+
+        # Same as (l+r)//2, but avoids overflow for 
+        # large l and h 
+        m = (l+(r-1))//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 = [12, 11, 13, 5, 6, 7] 
+n = len(arr) 
+print ("Given array is") 
+for i in range(n): 
+    print ("%d" %arr[i]), 
+
+mergeSort(arr,0,n-1) 
+print ("\n\nSorted array is") 
+for i in range(n): 
+    print ("%d" %arr[i]), 

Python/Selection_sort.py

@@ -0,0 +1,23 @@
+# Python program for implementation of Selection 
+# Sort 
+import sys 
+A = [64, 25, 12, 22, 11] 
+
+# Traverse through all array elements 
+for i in range(len(A)): 
+
+    # Find the minimum element in remaining  
+    # unsorted array 
+    min_idx = i 
+    for j in range(i+1, len(A)): 
+        if A[min_idx] > A[j]: 
+            min_idx = j 
+
+    # Swap the found minimum element with  
+    # the first element         
+    A[i], A[min_idx] = A[min_idx], A[i] 
+
+# Driver code to test above 
+print ("Sorted array") 
+for i in range(len(A)): 
+    print("%d" %A[i]),