Hash-based bisect debugging in compilers and runtimes(research.swtch.com)

    def bisect_dumb(p, s):
        end, need = len(s), []

        while True:
            need.sort()
            needed = [s[j] for j in need]
            last = first_satisfying_bisect(lambda i: p(s[:i] + needed), 0, end)
            if last == 0:
                return need

            end = last - 1
            need.append(end)

    def bisect_easy(p, s, targets=None, need=[]):
        if targets is None:
            targets = list(range(len(s)))
        if not targets or p([s[i] for i in sorted(need)]):
            return []
        if len(targets) == 1:
            return [targets[0]]

        m = len(targets)//2
        left, right = targets[:m], targets[m:]

        left_reduced = bisect_easy(p, s, left, right + need)
        right_reduced = bisect_easy(p, s, right, left_reduced + need)

        return left_reduced + right_reduced