Given a data stream input of non-negative integers a1, a2, ..., an, ..., summarize the numbers seen so far as a list of disjoint intervals.

For example, suppose the integers from the data stream are 1, 3, 7, 2, 6, ..., then the summary will be:

[1, 1]
[1, 1], [3, 3]
[1, 1], [3, 3], [7, 7]
[1, 3], [7, 7]
[1, 3], [6, 7]

 

Follow up:

What if there are lots of merges and the number of disjoint intervals are small compared to the data stream's size?

class SummaryRanges {
    // PriorityQueue<Integer> pq;
    List<Integer> list;
    
    /** Initialize your data structure here. */
    public SummaryRanges() {
        // pq = new PriorityQueue<>();
        list = new ArrayList();
        
    }
    
    public void addNum(int val) {
        // pq.offer(val);
        if(list.indexOf(val) < 0) list.add(val);
        Collections.sort(list);
//         for(int i = 0; i < list.size(); i++) {
            
//         }
    }
    
    public int[][] getIntervals() {
        // System.out.println(list.toString());
        List<int[]> res = new ArrayList();
        for(int i = 0; i < list.size(); i++) {
            int cur = i;
            while(cur+1 < list.size() && list.get(cur+1) - list.get(cur) == 1) cur++;
            if(cur != i) res.add(new int[]{list.get(i), list.get(cur)});
            else res.add(new int[]{list.get(i), list.get(i)});
            i = cur;
        }
        int[][] result = new int[res.size()][2];
        int j = 0;
        for(int[] tmp: res) result[j++] = tmp;
        return result;
    }
}

/**
 * Your SummaryRanges object will be instantiated and called as such:
 * SummaryRanges obj = new SummaryRanges();
 * obj.addNum(val);
 * int[][] param_2 = obj.getIntervals();
 */

1. first ver

Used an arraylist to store unique values, sort after every add. Then generate interval array step by step.