Today's Freebie. It's marked as easy.
This problem was asked by Amazon.
Run-length encoding is a fast and simple method of encoding strings. The basic idea is to represent repeated successive characters as a single count and character. For example, the string "AAAABBBCCDAA" would be encoded as "4A3B2C1D2A".
Implement run-length encoding and decoding. You can assume the string to be encoded have no digits and consists solely of alphabetic characters. You can assume the string to be decoded is valid.
Another Python Using Generators
"""Example using generators for run length encode/decode."""
def rleunits(str1):
"""Generate run length encoded units."""
current = None
count = 0
for letter in str1:
if letter == current:
count += 1
else:
if current:
yield str(count)+current
count = 1
current = letter
def rldunits(str1):
"""Generate run length decoded units."""
count = None
for c in str1:
if c.isdigit():
if not count:
count = c
else:
count += c
else:
yield(c * int(count))
count = None
def main():
"""Drive the example."""
str1 = "AAAABBBBCDDEEFFFFFFFFFFF"
encoded = ''.join(rleunits(str1))
print(encoded)
unencoded = ''.join(rldunits(encoded))
print(unencoded)
main()
