PAST2J

from Second Algorithm Practical Skills Test J - string parsing

PAST2J

• We can call it recursively with a function that handles the range enclosed by the parentheses.
• Access strings by subscripts instead of editing them directly
• AC python

def solve(S):
    N = len(S)
    cur = 0
    ret = []

    def parse_palen():
        nonlocal cur
        cur += 1
        ret = []
        while cur < N:
            c = S[cur]
            if c == ")":
                s = "".join(ret)
                s2 = "".join(reversed(s))
                return s + s2
            elif c == "(":
                ret.append(parse_palen())
            else:
                ret.append(c)
            cur += 1

    while cur < N:
        c = S[cur]
        if c == "(":
            ret.append(parse_palen())
        else:
            ret.append(c)
        cur += 1
    return "".join(ret)

9min

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