Mean, Median, Mode

use std::env;
use std::collections::HashMap;


fn main() {
    // Numbers to place in the vector will be passed
    // in via command line arguments.
    let args: Vec<String> = env::args().collect();

    let mut numbers: Vec<i32> = Vec::new();

    // Parse out the valid integers sent in via the command line.
    // Excludes the first argument (0) because that's just the name
    // of the program.
    for string in &args[1..] {
        match string.trim().parse::<i32>() {
            Ok(value) => numbers.push(value),
            Err(_) => {},
        }
    }

    // Enforce a sorted vector.
    numbers.sort();

    println!("Mean: {}", mean(&numbers));
    println!("Median: {}", median(&numbers));
    println!("Mode: {}", mode(&numbers));

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

fn mean(numbers: &Vec<i32>) -> i32 {
    if numbers.len() == 0 {
        return 0
    }

    let mut sum = 0;
    for &number in numbers {
        sum += number;
    }

    sum / numbers.len() as i32
}

fn median(numbers: &Vec<i32>) -> i32 {
    numbers[numbers.len() / 2]
}

fn mode(integers: &Vec<i32>) -> i32 {
    let mut numbers = HashMap::new();

    for integer in integers {
        let count = numbers.entry(integer).or_insert(0);
        *count += 1;
    }

    let mut mode = 0;
    let mut most_occurrences = 0;
    for (number, quantity) in numbers {
        if quantity > most_occurrences {
            most_occurrences = quantity;
            mode = *number;
        }
    }

    mode
}