psf/black code formatting (TheAlgorithms#1421)

* added sol3.py for problem_20

* added sol4.py for problem_06

* ran `black .` on `\Python`

ciphers/base64_cipher.py

@@ -18,7 +18,7 @@ def encode_base64(text):
     i = 0
     while i < len(s):
         if i > 0 and ((i / 3 * 4) % 76) == 0:
-            r = r + "\r\n" # for unix newline, put "\n"
+            r = r + "\r\n"  # for unix newline, put "\n"
 
         n = (s[i] << 16) + (s[i + 1] << 8) + s[i + 2]
 

ciphers/caesar_cipher.py

@@ -1,5 +1,5 @@
 def encrypt(input_string: str, key: int) -> str:
-    result = ''
+    result = ""
     for x in input_string:
         if not x.isalpha():
             result += x
@@ -11,7 +11,7 @@ def encrypt(input_string: str, key: int) -> str:
 
 
 def decrypt(input_string: str, key: int) -> str:
-    result = ''
+    result = ""
     for x in input_string:
         if not x.isalpha():
             result += x
@@ -24,23 +24,23 @@ def decrypt(input_string: str, key: int) -> str:
 
 def brute_force(input_string: str) -> None:
     key = 1
-    result = ''
+    result = ""
     while key <= 94:
         for x in input_string:
             indx = (ord(x) - key) % 256
             if indx < 32:
                 indx = indx + 95
             result = result + chr(indx)
-        print(f'Key: {key}\t| Message: {result}')
-        result = ''
+        print(f"Key: {key}\t| Message: {result}")
+        result = ""
         key += 1
     return None
 
 
 def main():
     while True:
         print(f'{"-" * 10}\n Menu\n{"-", * 10}')
-        print(*["1.Encrpyt", "2.Decrypt", "3.BruteForce", "4.Quit"], sep='\n')
+        print(*["1.Encrpyt", "2.Decrypt", "3.BruteForce", "4.Quit"], sep="\n")
         choice = input("What would you like to do?: ")
         if choice not in ["1", "2", "3", "4"]:
             print("Invalid choice, please enter a valid choice")

data_structures/binary_tree/treap.py

@@ -7,6 +7,7 @@ class Node(object):
     Treap's node
     Treap is a binary tree by value and heap by priority
     """
+
     def __init__(self, value: int = None):
         self.value = value
         self.prior = random()
@@ -20,10 +21,7 @@ def __repr__(self):
             return "'%s: %.5s'" % (self.value, self.prior)
         else:
             return pformat(
-                {
-                    "%s: %.5s"
-                    % (self.value, self.prior): (self.left, self.right)
-                },
+                {"%s: %.5s" % (self.value, self.prior): (self.left, self.right)},
                 indent=1,
             )
 
@@ -33,6 +31,7 @@ def __str__(self):
         right = str(self.right or "")
         return value + left + right
 
+
 def split(root: Node, value: int) -> Tuple[Node, Node]:
     """
     We split current tree into 2 trees with value:
@@ -61,12 +60,13 @@ def split(root: Node, value: int) -> Tuple[Node, Node]:
             root.right, right = split(root.right, value)
             return (root, right)
 
+
 def merge(left: Node, right: Node) -> Node:
     """
     We merge 2 trees into one.
     Note: all left tree's values must be less than all right tree's
     """
-    if (not left) or (not right):   # If one node is None, return the other
+    if (not left) or (not right):  # If one node is None, return the other
         return left or right
     elif left.prior < right.prior:
         """
@@ -82,6 +82,7 @@ def merge(left: Node, right: Node) -> Node:
         right.left = merge(left, right.left)
         return right
 
+
 def insert(root: Node, value: int) -> Node:
     """
     Insert element
@@ -94,6 +95,7 @@ def insert(root: Node, value: int) -> Node:
     left, right = split(root, value)
     return merge(merge(left, node), right)
 
+
 def erase(root: Node, value: int) -> Node:
     """
     Erase element
@@ -102,15 +104,16 @@ def erase(root: Node, value: int) -> Node:
     Split all nodes with values greater into right.
     Merge left, right
     """
-    left, right = split(root, value-1)
+    left, right = split(root, value - 1)
     _, right = split(right, value)
     return merge(left, right)
 
+
 def inorder(root: Node):
     """
     Just recursive print of a tree
     """
-    if not root:    # None
+    if not root:  # None
         return
     else:
         inorder(root.left)
@@ -154,21 +157,26 @@ def interactTreap(root, args):
 
     return root
 
+
 def main():
     """After each command, program prints treap"""
     root = None
-    print("enter numbers to creat a tree, + value to add value into treap, - value to erase all nodes with value. 'q' to quit. ")
+    print(
+        "enter numbers to creat a tree, + value to add value into treap, - value to erase all nodes with value. 'q' to quit. "
+    )
 
     args = input()
-    while args != 'q':
+    while args != "q":
         root = interactTreap(root, args)
         print(root)
         args = input()
 
     print("good by!")
     pass
 
+
 if __name__ == "__main__":
     import doctest
+
     doctest.testmod()
     main()

divide_and_conquer/mergesort.py

@@ -1,45 +1,48 @@
-def merge(a,b,m,e):
-    l=a[b:m+1]
-    r=a[m+1:e+1]
-    k=b
-    i=0
-    j=0
-    while i<len(l) and j<len(r):
-        #change sign for Descending order
-        if l[i]<r[j]: 
-            a[k]=l[i]
-            i+=1
+def merge(a, b, m, e):
+    l = a[b : m + 1]
+    r = a[m + 1 : e + 1]
+    k = b
+    i = 0
+    j = 0
+    while i < len(l) and j < len(r):
+        # change sign for Descending order
+        if l[i] < r[j]:
+            a[k] = l[i]
+            i += 1
         else:
-            a[k]=r[j]
-            j+=1
-        k+=1
-    while i<len(l):
-        a[k]=l[i]
-        i+=1
-        k+=1
-    while j<len(r):
-        a[k]=r[j]
-        j+=1
-        k+=1
+            a[k] = r[j]
+            j += 1
+        k += 1
+    while i < len(l):
+        a[k] = l[i]
+        i += 1
+        k += 1
+    while j < len(r):
+        a[k] = r[j]
+        j += 1
+        k += 1
     return a
-
-def mergesort(a,b,e):
+
+
+def mergesort(a, b, e):
     """
     >>> mergesort([3,2,1],0,2)
     [1, 2, 3]
     >>> mergesort([3,2,1,0,1,2,3,5,4],0,8)
     [0, 1, 1, 2, 2, 3, 3, 4, 5]
     """
-    if b<e:
-        m = (b+e)//2
-        #print("ms1",a,b,m)
-        mergesort(a,b,m)
-        #print("ms2",a,m+1,e)
-        mergesort(a,m+1,e)
-        #print("m",a,b,m,e)
-        merge(a,b,m,e)
+    if b < e:
+        m = (b + e) // 2
+        # print("ms1",a,b,m)
+        mergesort(a, b, m)
+        # print("ms2",a,m+1,e)
+        mergesort(a, m + 1, e)
+        # print("m",a,b,m,e)
+        merge(a, b, m, e)
         return a
 
+
 if __name__ == "__main__":
     import doctest
+
     doctest.testmod()

dynamic_programming/abbreviation.py

@@ -11,6 +11,7 @@
 daBcd -> capitalize a and c(dABCd) -> remove d (ABC)
 """
 
+
 def abbr(a, b):
     """
     >>> abbr("daBcd", "ABC")

dynamic_programming/fibonacci.py

@@ -58,7 +58,7 @@ def get(self, sequence_no=None):
                 print("\nInvalid input, please try again.")
     except NameError:
         print("\n********* Invalid input, good bye!! ************\n")
-        
+
     import doctest
 
     doctest.testmod()

dynamic_programming/fractional_knapsack.py

@@ -20,6 +20,7 @@ def fracKnapsack(vl, wt, W, n):
         else sum(vl[:k])
     )
 
+
 if __name__ == "__main__":
     import doctest
 

dynamic_programming/longest_common_subsequence.py

@@ -76,7 +76,7 @@ def longest_common_subsequence(x: str, y: str):
     expected_subseq = "GTAB"
 
     ln, subseq = longest_common_subsequence(a, b)
-##    print("len =", ln, ", sub-sequence =", subseq)
+    ##    print("len =", ln, ", sub-sequence =", subseq)
     import doctest
 
     doctest.testmod()

dynamic_programming/sum_of_subset.py

@@ -29,6 +29,7 @@ def isSumSubset(arr, arrLen, requiredSum):
     #     print(subset[i])
     print(subset[arrLen][requiredSum])
 
+
 if __name__ == "__main__":
     import doctest