class Solution:
    def reverseParentheses(self, s: str) -> str:
        lefts = []
        pairs = {}

        for i, c in enumerate(s):
            if c == '(':
                lefts.append(i)
            elif c == ')':
                left = lefts.pop()
                pairs[left] = i
                pairs[i] = left

        # teleport when pair matches
        # ex: a(bc)d
        # a -> ( teleport to ) -> c b -> ( teleport to ) -> end
        # ex: [a(bc)d]
        # [ teleport to ] -> d -> ) teleport to ( -> b c ->
        # ) teleport to ( -> a -> [ teleport to ] -> end
        ans = []
        idx = 0
        step = 1
        while 0 <= idx < len(s):
            if idx in pairs: # teleport
                idx = pairs[idx]
                step = -step
            else:
                ans.append(s[idx])

            idx += step # move next, skip ()

        return "".join(ans)