[LeetCode]The Skyline Problem

public class Solution {
    public List<int[]> getSkyline(int[][] buildings) {
        List<int[]> height = new ArrayList<int[]>();
        List<int[]> result = new ArrayList<int[]>();
        for (int[] tmp : buildings) {
            height.add(new int[]{tmp[0], tmp[2]});
            height.add(new int[]{tmp[1], -tmp[2]});
        }
        Collections.sort(height, new Comparator<int[]>() {
            public int compare(int[] o1, int[] o2) {
                if (o1[0] != o2[0]) {
                    return o1[0] - o2[0];
                } else {
                    return o2[1] - o1[1];
                }
            }
        });
        Queue<Integer> queue = new PriorityQueue<Integer>(1, new Comparator<Integer>() {
            public int compare(Integer o1, Integer o2) {
                return o2 - o1;
            }    
        });
        int pre = 0;
        queue.offer(0);
        for (int[] tmp : height) {
            if (tmp[1] > 0) {
                queue.offer(tmp[1]);
            } else {
                queue.remove(-tmp[1]);
            }
            int cur = queue.peek();
            if (cur != pre) {
                result.add(new int[]{tmp[0], cur});
                pre = cur;
            }
        }
        return result;
    }
}