lst-0033-book.cpp
// https://godbolt.org/z/jjWx3d375
vector d{ 1, 2, 4, -1, 1, 2, -2 };
for(size_t idx=0; idx < d.size(); ) { // checks vector boundary
cout << d[idx] << ' '; // additional check with at not necessary
idx += d[idx]; // same here
}
cout << '\n';
// Output: 1 2 -1 4 -2 1 2