Cargo.toml

[package]
name = "first"
version = "0.1.0"
authors = ["Your Name <you@example.com>"]

[dependencies]
serde = "1.0.81"
serde_json = "1.0.33"
serde_derive = "1.0.81"

data-analyitics.rs

use std::io;
use std::io::BufRead;
#[macro_use]
extern crate serde_derive;

extern crate serde;
extern crate serde_json;

#[derive(Serialize, Deserialize, Debug)]
struct Stats {
    max: f64,
    mean: f64,
    min: f64,
    size: u64,
    sum: f64,
}

impl Stats {
    fn new() -> Stats {
        return Stats {
            max: 0f64,
            min: 0f64,
            size: 0,
            sum: 0f64,
            mean: 0f64,
        };
    }

    fn update(&mut self, val: f64) {
        if self.max < val {
            self.max = val;
        }

        if self.min > val {
            self.min = val;
        }

        self.sum = self.sum + val;

        self.size += 1;

        self.mean = self.sum / (self.size as f64);
    }
}

fn main() {
    let mut stats = Stats::new();

    let stdin = io::stdin();
    for line in stdin.lock().lines() {
        let num: f64 = line.unwrap().parse().unwrap();
        stats.update(num);
    }

    println!("{:?}", stats);
    let serialized = serde_json::to_string(&stats).unwrap();
    println!("{}", serialized);
}