Editing base64, Adding average file, Editing find_lcm (#673)

* avrage.py

calculate and print the avrage of number list.

* Update base64_cipher.py

encoding and decoding base64 without any module.

* Update and rename avrage.py to average.py

* update find_lcm algorithm

I made find_lcm more efficient form O(num1*num2) to O(min{num1,num2}).

Maths/average.py

@@ -0,0 +1,14 @@
+def average(nums):
+    sum = 0
+    n = 0
+    for x in nums:
+      sum += x
+      n += 1
+    avg = sum / n
+    print(avg)
+
+def main():
+  average([2, 4, 6, 8, 20, 50, 70])
+
+if __name__ == '__main__':
+  main()

Maths/find_lcm.py

@@ -1,10 +1,11 @@
 def find_lcm(num_1, num_2):
     max = num_1 if num_1 > num_2 else num_2
+    lcm = max
     while (True):
-        if ((max % num_1 == 0) and (max % num_2 == 0)):
+        if ((lcm % num_1 == 0) and (lcm % num_2 == 0)):
             break
-        max += 1
-    return max
+        lcm += max
+    return lcm
 
 
 def main():

ciphers/base64_cipher.py

@@ -1,11 +1,64 @@
-import base64
+def encodeBase64(text):
+    base64chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
+    
+    r = "" #the result
+    c = 3 - len(text) % 3 #the length of padding
+    p = "=" * c #the padding
+    s = text + "\0" * c #the text to encode
+    
+    i = 0   
+    while i < len(s):
+        if i > 0 and ((i / 3 * 4) % 76) == 0:
+            r = r + "\r\n"
+        
+        n = (ord(s[i]) << 16) + (ord(s[i+1]) << 8 ) + ord(s[i+2])
+        
+        n1 = (n >> 18) & 63
+        n2 = (n >> 12) & 63
+        n3 = (n >> 6)  & 63
+        n4 = n & 63
+        
+        r += base64chars[n1] + base64chars[n2] + base64chars[n3] + base64chars[n4]
+        i += 3
+
+    return r[0: len(r)-len(p)] + p
+    
+def decodeBase64(text):
+    base64chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
+    s = ""
+    
+    for i in text:
+        if i in base64chars:
+            s += i
+            c = ""
+        else:
+            if i == '=':
+                c += '='
+    
+    p = ""
+    if c == "=":
+        p = 'A'
+    else:
+        if c == "==":
+            p = "AA"
+    
+    r = ""
+    s = s + p
+   
+    i = 0
+    while i < len(s):
+        n = (base64chars.index(s[i]) << 18) +  (base64chars.index(s[i+1]) << 12) +  (base64chars.index(s[i+2]) << 6) +base64chars.index(s[i+3])
+        
+        r += chr((n >> 16) & 255) + chr((n >> 8) & 255) + chr(n & 255)
+        
+        i += 4
+    
+    return r[0: len(r) - len(p)]
 
 def main():
-    inp = input('->')
-    encoded = inp.encode('utf-8') #encoded the input (we need a bytes like object)
-    b64encoded = base64.b64encode(encoded) #b64encoded the encoded string
-    print(b64encoded)
-    print(base64.b64decode(b64encoded).decode('utf-8'))#decoded it
+    print(encodeBase64("WELCOME to base64 encoding"))
+    print(decodeBase64(encodeBase64("WELCOME to base64 encoding")))
+    
 
 if __name__ == '__main__':
     main()