def indice(lettre, ordre):
    for i in range(len(ordre)):
        if ordre[i] == lettre:
            return i

def comparer (mot1, mot2, ordre):
    i= 0
    while i < len(mot1) and i < len(mot2):
        il = indice(mot1[i], ordre)
        i2 = indice(mot2[i], ordre)
        if il < i2:
            return True
        elif il > i2:
            return False
        i += 1
    return len(mot1) < len(mot2)

def premiere_diff(mot1, mot2):
    i= 0
    while i < len(mot1) and i < len(mot2):
        if mot1[i] != mot2[i]:
            return i
        i += 1
    return min(len(mot1), len(mot2))

def dico_adj(mots):
    adj = {}
    for (mot1, mot2) in mots:
        ident = premiere_diff(mot1, mot2)
        if ident < len(mot1) and ident < len(mot2):
            petite = mot1[ident]
            grande = mot2[ident]
            if petite not in adj:
                adj[petite] = [grande]
            else:
                adj[petite].append(grande)
    return adj

def parcours(adj, s, deja_vus, tri):
    if s in adj:
        for v in adj[s]:
            if v not in deja_vus:
                deja_vus.append(v)
                parcours(adj, v, deja_vus, tri)
    tri.append(s)

def trier(mots):
    adj = dico_adj(mots)
    tri = []
    deja_vus = []
    for s in adj:
        if s not in deja_vus:
            deja_vus.append(s)
            parcours(adj, s, deja_vus, tri)
    tri.reverse()
    return tri

mots_exemple = [("oou", "ooai"), ("yee", "ieo"), ("ye", "aaaa"), ("a", "ieo"), ("euee", "eyy"), ("ao", "au"), ("e", "a")]

# print(dico_adj(mots_exemple))

print(trier(mots_exemple))