process_str_special_op2.py (1544B)
| # 3614. Process String with Special Operations II
"""
you are given a string 's' consisting of lowercase english letters and the
special characters '*', '#', and '%'. you are also given an integer 'k'.
build a new string 'result' by processing 's' according to the following
rules from left to right: if the letter is a lowercase english letter append
it to 'result'. a '*' removes the last character from 'result'. a '#'
duplicates the current 'result' and appends it to itself. a '%' reverses the
current 'result'. return the k'th character of the final string 'result'. if
'k' is out of the bounds of 'result', return '.'.
"""
class Solution:
def processStr(self, s: str, k: int) -> str:
l, p = 0, k
for c in s:
if c == "*":
if l > 0:
l -= 1
elif c == "#":
l *= 2
elif c == "%":
pass
else:
l += 1
if k >= l:
return "."
for c in s[::-1]:
if c == "*":
l += 1
elif c == "#":
if p >= l // 2:
p -= l // 2
l = l // 2
elif c == "%":
p = (l - 1) - p
else:
if l == p + 1:
return c
l -= 1
return s[p]
if __name__ == "__main__":
obj = Solution()
print(obj.processStr(s="a#b%*", k=1))
print(obj.processStr(s="cd%#*#", k=3))
print(obj.processStr(s="z*#", k=0))
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