error[E0502]: cannot borrow `v` as immutable because it is also borrowed as mutable エラーが出たのでメモ。やりたいこと。 fn main() { let mut v: Vec<usize> = vec![3, 123, 234, 345, 456, 567]; v[v[0]] *= 100; // 要素 3 を 100 倍する println!("{:?}"</usize>…