Add new algorithm, data structure, cipher, puzzle (Hacktoberfest accepted) #3474

Array.py

@@ -0,0 +1,30 @@
+# Initialize an array with 5 elements
+my_array = [10, 20, 30, 40, 50]
+
+# Access array elements
+print(my_array[0])   # Output: 10
+print(my_array[3])   # Output: 40
+
+# Search for an element
+element_to_search = 30
+if element_to_search in my_array:
+    print(f"Element {element_to_search} found at index {my_array.index(element_to_search)}")
+else:
+    print(f"Element {element_to_search} not found")
+
+# Sort the array
+sorted_array = sorted(my_array)
+print(sorted_array)  # Output: [10, 20, 30, 40, 50]
+
+# Insert an element
+my_array.append(60)
+print(my_array)      # Output: [10, 20, 30, 40, 50, 60]
+
+# Delete an element
+del my_array[2]
+print(my_array)      # Output: [10, 20, 40, 50, 60]
+
+# Resize the array
+my_array = [1, 2, 3, 4, 5]
+my_array = my_array[:3]    # Resize array to first 3 elements
+print(my_array)            # Output: [1, 2, 3]

cipher.py

@@ -0,0 +1,57 @@
+def caesar_cipher(plaintext, shift):
+    ciphertext = ""
+    for char in plaintext:
+        if char.isalpha():
+            if char.isupper():
+                ciphertext += chr((ord(char) - 65 + shift) % 26 + 65)
+            else:
+                ciphertext += chr((ord(char) - 97 + shift) % 26 + 97)
+        else:
+            ciphertext += char
+    return ciphertext
+def vigenere_cipher(plaintext, key):
+    ciphertext = ""
+    key_index = 0
+    for char in plaintext:
+        if char.isalpha():
+            if char.isupper():
+                shift = ord(key[key_index % len(key)].upper()) - 65
+                ciphertext += chr((ord(char) - 65 + shift) % 26 + 65)
+            else:
+                shift = ord(key[key_index % len(key)].lower()) - 97
+                ciphertext += chr((ord(char) - 97 + shift) % 26 + 97)
+            key_index += 1
+        else:
+            ciphertext += char
+    return ciphertext
+def create_playfair_matrix(keyword):
+    alphabet = "ABCDEFGHIKLMNOPQRSTUVWXYZ"
+    matrix = []
+    for char in keyword.upper():
+        if char not in matrix and char in alphabet:
+            matrix.append(char)
+    for char in alphabet:
+        if char not in matrix:
+            matrix.append(char)
+    playfair_matrix = [matrix[i:i+5] for i in range(0, 25, 5)]
+    return playfair_matrix
+
+def playfair_cipher(plaintext, keyword):
+    playfair_matrix = create_playfair_matrix(keyword)
+    ciphertext = ""
+    plaintext = plaintext.upper().replace("J", "I")
+    plaintext = plaintext.replace(" ", "")
+    plaintext = plaintext + "X" if len(plaintext) % 2 != 0 else plaintext
+    for i in range(0, len(plaintext), 2):
+        row1, col1 = divmod(playfair_matrix.index(playfair_matrix[int(playfair_matrix.index(plaintext[i])/5)]), 5)
+        row2, col2 = divmod(playfair_matrix.index(playfair_matrix[int(playfair_matrix.index(plaintext[i+1])/5)]), 5)
+        if row1 == row2:
+            ciphertext += playfair_matrix[row1][(col1+1)%5]
+            ciphertext += playfair_matrix[row2][(col2+1)%5]
+        elif col1 == col2:
+            ciphertext += playfair_matrix[(row1+1)%5][col1]
+            ciphertext += playfair_matrix[(row2+1)%5][col2]
+        else:
+            ciphertext += playfair_matrix[row1][col2]
+            ciphertext += playfair_matrix[row2][col1]
+    return ciphertext

crit-bit tree.py

@@ -0,0 +1,45 @@
+# Define a class for the nodes in the tree
+class CritBitNode:
+    def _init_(self, key=None, terminal=False):
+        self.key = key
+        self.left_child = None
+        self.right_child = None
+        self.terminal = terminal
+
+# Define a class for the tree
+class CritBitTree:
+    def _init_(self):
+        self.root = None
+
+    # Insert a key into the tree
+    def insert(self, key):
+        if self.root is None:
+            self.root = CritBitNode(key)
+        else:
+            current_node = self.root
+            while True:
+                if key < current_node.key:
+                    if current_node.left_child is None:
+                        current_node.left_child = CritBitNode(key)
+                        break
+                    else:
+                        current_node = current_node.left_child
+                else:
+                    if current_node.right_child is None:
+                        current_node.right_child = CritBitNode(key)
+                        break
+                    else:
+                        current_node = current_node.right_child
+            current_node.terminal = True
+
+    # Search for a key in the tree
+    def search(self, key):
+        current_node = self.root
+        while current_node is not None:
+            if key == current_node.key:
+                return current_node.terminal
+            elif key < current_node.key:
+                current_node = current_node.left_child
+            else:
+                current_node = current_node.right_child
+        return False