Solution.java

class Solution {
    public long minCost(int[] basket1, int[] basket2) {
        int n = basket1.length;
        Map<Integer, Integer> cnt = new HashMap<>();
        for (int i = 0; i < n; ++i) {
            cnt.merge(basket1[i], 1, Integer::sum);
            cnt.merge(basket2[i], -1, Integer::sum);
        }
        int mi = 1 << 30;
        List<Integer> nums = new ArrayList<>();
        for (var e : cnt.entrySet()) {
            int x = e.getKey(), v = e.getValue();
            if (v % 2 != 0) {
                return -1;
            }
            for (int i = Math.abs(v) / 2; i > 0; --i) {
                nums.add(x);
            }
            mi = Math.min(mi, x);
        }
        Collections.sort(nums);
        int m = nums.size();
        long ans = 0;
        for (int i = 0; i < m / 2; ++i) {
            ans += Math.min(nums.get(i), mi * 2);
        }
        return ans;
    }
}