mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-24 05:21:09 +00:00
c92b02cfa3
* 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}).
65 lines
1.6 KiB
Python
65 lines
1.6 KiB
Python
def encodeBase64(text):
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base64chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
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r = "" #the result
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c = 3 - len(text) % 3 #the length of padding
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p = "=" * c #the padding
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s = text + "\0" * c #the text to encode
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i = 0
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while i < len(s):
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if i > 0 and ((i / 3 * 4) % 76) == 0:
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r = r + "\r\n"
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n = (ord(s[i]) << 16) + (ord(s[i+1]) << 8 ) + ord(s[i+2])
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n1 = (n >> 18) & 63
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n2 = (n >> 12) & 63
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n3 = (n >> 6) & 63
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n4 = n & 63
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r += base64chars[n1] + base64chars[n2] + base64chars[n3] + base64chars[n4]
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i += 3
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return r[0: len(r)-len(p)] + p
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def decodeBase64(text):
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base64chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
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s = ""
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for i in text:
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if i in base64chars:
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s += i
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c = ""
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else:
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if i == '=':
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c += '='
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p = ""
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if c == "=":
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p = 'A'
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else:
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if c == "==":
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p = "AA"
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r = ""
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s = s + p
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i = 0
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while i < len(s):
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n = (base64chars.index(s[i]) << 18) + (base64chars.index(s[i+1]) << 12) + (base64chars.index(s[i+2]) << 6) +base64chars.index(s[i+3])
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r += chr((n >> 16) & 255) + chr((n >> 8) & 255) + chr(n & 255)
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i += 4
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return r[0: len(r) - len(p)]
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def main():
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print(encodeBase64("WELCOME to base64 encoding"))
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print(decodeBase64(encodeBase64("WELCOME to base64 encoding")))
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if __name__ == '__main__':
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main()
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