is_blank.rs

// Best real time: 0.46s
use std::fs::File;
use std::io::{BufRead, BufReader};

fn is_blank(s: &str) -> bool {
    s.chars().all(|c| c.is_whitespace())
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let file = File::open("biggest.txt")?;
    let mut file = BufReader::new(file);
    let mut line = String::new();
    let mut k = 0_u32;
    while file.read_line(&mut line)? > 0 {
        if is_blank(&line) {
            k += 1;
        }
        line.clear();
    }
    println!("{}", k);
    Ok(())
}