use std::collections::BTreeMap;

fn mean(nums: &[i32]) -> f32 {
    let mut nums = nums.to_vec();
    nums.sort();
    let len = nums.len();
    if len % 2 == 0 {
        (nums[len/2] + nums[len/2+1]) as f32 / 2 as f32
    } else {
        nums[len/2] as f32
    }
}

fn average(nums: &[i32]) -> f32 {
    nums.iter().sum::<i32>() as f32 / nums.len() as f32
}

fn mode(nums: &[i32]) -> i32 {
    let mut occurrences = BTreeMap::new();
    for num in nums {
        let count = occurrences.entry(num).or_insert(0);
        *count += 1;
    }
    occurrences.iter().rev().next().unwrap().key()
}

fn main() {
    let nums = vec![9, 7, 5, 5, 3, 1];
    println!("Numbers: {:?}", nums);
    println!("Mean: {}", mean(&nums));
    println!("Average: {}", average(&nums));
}