use std::cmp::min;
use std::collections::HashMap;

struct Solution;
impl Solution {
    pub fn min_cost(basket1: Vec<i32>, basket2: Vec<i32>) -> i64 {
        let mut map : HashMap<i32,i32> = HashMap::new();
        let mut total_cost: i64 = 0;
        let mut min_cost = i32::MAX;
        for i in basket1.iter() {
            *map.entry(*i).or_insert(0) += 1;
        }
        for i in basket2.iter() {
            *map.entry(*i).or_insert(0) -= 1;
        }
        let mut kvs: Vec<(i32, i32)> = map.iter().filter(|(k, v)| {min_cost = min(min_cost, **k); if **v == 0 {false} else {true}}).map(|(k, v)| (*k, *v)).collect();
        let mut err = false;
        kvs.sort_by(|a, b| {
            err |= b.1 % 2 == 1 || a.1 % 2 == 1;
            if a.1 > 0 && b.1 < 0 {
                std::cmp::Ordering::Greater
            } else if a.1 < 0 && b.1 > 0 {
                std::cmp::Ordering::Less
            } else {
                a.0.cmp(&b.0)
            }
        });
        if err
        { return -1; }
        if kvs.is_empty() {
            return 0;
        }
        let mut l = 0;
        let mut r = kvs.len() - 1;
        while l < r {
            let cost = min( kvs[l].1.abs(), kvs[r].1.abs()) as i64;
            total_cost += min(min(kvs[l].0, kvs[r].0) as i64 * cost / 2,min_cost as i64 * cost);
            kvs[l].1 += cost as i32;
            kvs[r].1 -= cost as i32;
            if kvs[l].1 >= 0 {
                l+=1;
            }
            if kvs[r].1 <= 0 {
                r-=1;
            }
        }
        if kvs[l].1 > 0 || kvs[r].1 > 0 { -1 } else { total_cost }
    }
}

fn main() {
    let sl = Solution::min_cost(vec![4,2,2,2], vec![1,4,1,2]);
    println!("{:?}", sl);
}