https://codereview.stackexchange.com/a/201749/35991

permutations.py

def from_permutation_to_disjoints_cycles(perm):
    mappings = { a: b for a, b in zip(*perm) }
    cycles = []
    for a in perm[0]:
        b = mappings.pop(a, None)
        if b is None:
            continue # `a` has already been handled
        cycle = [a]
        while a != b:
            cycle.append(b)
            b = mappings.pop(b)
        cycles.append(cycle)
    return cycles