- Using a traditional for loop. There are no lifetime issues, because a new reference is acquired on each iteration. The reserve is not required, but I included it to match your C++ version. https://play.rust-lang.org/?version=stable&mode=debug&editio...
- Repeating the vector using the built-in method `Vec::repeat`. This allocates a new vector, but `reserve` is likely to do the same, just implicitly.
https://play.rust-lang.org/?version=stable&mode=debug&editio...
- Using a traditional for loop. There are no lifetime issues, because a new reference is acquired on each iteration. The reserve is not required, but I included it to match your C++ version. https://play.rust-lang.org/?version=stable&mode=debug&editio...
- Creating an array of slices and then concatenating them into a new Vec using the concat method on slices: https://play.rust-lang.org/?version=stable&mode=debug&editio...