将Map<Vec<u8>，Vec<u8>>展平为Vec<u8>，然后将其返回到Map<Vec<u8>，Vec<u8>>

use std::collections::HashMap;

fn flatten_map(map: &HashMap<Vec<u8>, Vec<u8>>) -> Vec<u8> {
    let mut flattened: Vec<u8> = Vec::new();
    for (key, value) in map.iter() {
        flattened.extend_from_slice(key);
        flattened.extend_from_slice(value);
    }
    flattened
}

fn main() {
    let mut map: HashMap<Vec<u8>, Vec<u8>> = HashMap::new();
    let key1 = vec![1, 2, 3];
    let value1 = vec![4, 5, 6];
    let key2 = vec![7, 8, 9];
    let value2 = vec![10, 11, 12];
    map.insert(key1.clone(), value1.clone());
    map.insert(key2.clone(), value2.clone());

    let flattened_map = flatten_map(&map);

    println!("{:?}", flattened_map);

    // 可以根据需要将展平后的Vec<u8>转换回Map<Vec<u8>, Vec<u8>>结构
    let mut reconstructed_map: HashMap<Vec<u8>, Vec<u8>> = HashMap::new();
    for i in (0..flattened_map.len()).step_by(6) {
        let key = flattened_map[i..(i + 3)].to_vec();
        let value = flattened_map[(i + 3)..(i + 6)].to_vec();
        reconstructed_map.insert(key, value);
    }

    println!("{:?}", reconstructed_map);
}