Sum of Distances

class Solution {
    public long[] distance(int[] nums) {
        HashMap<Integer, List<Integer>> hmap = new HashMap<>();
        // O(n)
        for(int i=0; i<nums.length; i++) {
            // O(n)
            if(!hmap.containsKey(nums[i]))
                hmap.put(nums[i], new ArrayList<>());
            hmap.get(nums[i]).add(i);
        }

        long ans[] = new long[nums.length];

        for(List<Integer> list : hmap.values()) {
            // O(n)
            int n = list.size();
            // [0,2,3,5,6]

            long leftsum = 0l;
            long rightsum = 0l;

            for(int i=0; i<n; i++) {
                rightsum += list.get(i);
            }

            for(int i=0; i<n; i++) {

                rightsum -= list.get(i);

                long currsum = 0l;

                // left side

                currsum += ((long)list.get(i)*i - leftsum);

                // right side

                currsum += (rightsum - (n-i-1)*(long)list.get(i));

                leftsum += list.get(i);

                ans[list.get(i)] = currsum;

            }


        }

        return ans;
    }
}