73 lines
1.7 KiB
Python
73 lines
1.7 KiB
Python
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# Based on https://github.com/AllAlgorithms, python/algorithms/math/railfence_cipher.py
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def railencrypt(st: str, k: int) -> str:
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assert k > 1
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c = 0
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x = 0
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m =[[0] * (len(st)) for i in range(k)]
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for r in range(len(st)):
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m[c][r] = ord(st[r])
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if x == 0:
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if c == (k-1):
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x = 1
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c -= 1
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else:
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c += 1
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else:
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if c == 0:
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x = 0
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c += 1
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else:
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c -= 1
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result = []
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for i in range(k):
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for j in range(len(st)):
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if m[i][j] != 0:
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result.append(chr(m[i][j]))
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return ''.join(result)
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def raildecrypt(st: str, k: int) -> str:
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assert k > 1
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c , x = 0 , 0
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m =[[0] * (len(st)) for i in range(k)]
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for r in range(len(st)):
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m[c][r] = 1
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if x == 0:
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if c == (k-1):
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x = 1
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c -= 1
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else:
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c += 1
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else:
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if c == 0:
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x = 0
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c += 1
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else:
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c -= 1
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result = []
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c , x = 0 , 0
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for i in range(k):
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for j in range(len(st)):
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if m[i][j] == 1:
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m[i][j] = ord(st[x])
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x += 1
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for r in range(len(st)):
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if m[c][r] != 0:
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result.append(chr(m[c][r]))
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if x == 0:
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if c == (k-1):
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x = 1
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c -= 1
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else:
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c += 1
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else:
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if c == 0:
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x = 0
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c += 1
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else:
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c -= 1
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return ''.join(result)
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