leetcode 939. Minimum Area Rectangle

I hate geometric problems…...

    class Solution {
        public int minAreaRect(int[][] points) {
            Map<Integer, List<Integer>> xmap = new HashMap<>();
            Map<Integer, List<Integer>> ymap = new HashMap<>();
            Set<String> s = new HashSet<>();
            for (int i = 0; i < points.length; ++i) {
                List<Integer> x = xmap.getOrDefault(points[i][0], new ArrayList<>());
                List<Integer> y = ymap.getOrDefault(points[i][1], new ArrayList<>());
                x.add(i);
                y.add(i);
                xmap.put(points[i][0], x);
                ymap.put(points[i][1], y);
                s.add(Arrays.toString(points[i]));
            }
            int[] tmp = new int[2];
            int ret = Integer.MAX_VALUE;
            for (int i = 0; i < points.length; ++i) {
                for (Integer right: ymap.getOrDefault(points[i][1], new ArrayList<>())) {
                    if (points[right][0] <= points[i][0]) continue;
                    for (Integer up: xmap.getOrDefault(points[i][0], new ArrayList<>())) {
                        if (points[up][1] <= points[i][1]) continue;
                        tmp[0] = points[right][0];
                        tmp[1] = points[up][1];
                        if (s.contains(Arrays.toString(tmp))) {
                            //compute size
                            ret = Math.min(ret, (tmp[0] - points[i][0]) * (tmp[1] - points[i][1]));
                        }
                    }
                }
            }
            return ret == Integer.MAX_VALUE? 0: ret;
        }
    }