perm("abc", "012") == "abc"
perm("abc", "210") == "cba"
perm("abc", "201") == "cab"

array<int, 10> perm{ 2,7,4,9,8,3,5,0,6,1 };
array<int, 10> perm_inverse;
for (int i = 0; i < 10; ++i) perm_inverse[perm[i]] = i;
for (int i = 0; i < 10; ++i) cout << perm_inverse[i] << ",";

While ( seq_c!= end )
{
if( perm(perm(str, seq), seq_c) == str)
return seq_c;
++seq_c;
}