Function hash1

publication/code/chapter06/hash.rs:3–10

(ascii_str: &str,  size: usize)

// hash.rs

fn hash1(ascii_str: &str,  size: usize) -> usize {
    let mut sum = 0;
    for c in ascii_str.chars() {
        sum += c as usize;
    }

    sum % size
}

// hash1 的迭迭代形式
fn hash1_iter(ascii_str: &str, size: usize) -> usize {