Untangle

sol.py

sequence="""
SRSRRSSRSRSSRSSRRSSRSSSSSRSSRSSRSRSSRSSRSSSSSSSSRSSRSSSSSRSSRSSRRSSRSSSSSRSSRSSRSSSSSSSSSSSSSSSSSRSSRSSRS
"""

from fractions import Fraction

def decode(seq):
    x = 0
    for nr in seq:
        if nr == 'S':
            if x == "inf":
                print(x)
                continue
            x = x + 1
        elif nr == "R":
            if x == "inf":
                x = 0
            elif x == 0:
                x = "inf"
            else:
                x = 0 - Fraction(1, x)
        print(x)
    return x

pq = decode(sequence)
res = []
while pq != 0:
    if pq < 0:
        res.append("S")
        pq = pq + 1
    else:
        pq = 0 - Fraction(1, pq)
        res.append("R")
       
print("".join(res))