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?
Solution:
/**
* Definition for an interval.
* public class Interval {
* int start;
* int end;
* Interval() { start = 0; end = 0; }
* Interval(int s, int e) { start = s; end = e; }
* }
*/
public class SummaryRanges {
TreeSet<Interval> ts;
/** Initialize your data structure here. */
public SummaryRanges() {
ts = new TreeSet<>(new Comparator<Interval>(){
@Override
public int compare(Interval i1, Interval i2){
return i1.start-i2.start;
}
});
}
public void addNum(int val) {
Interval i = new Interval(val, val);
Interval low = ts.floor(i);
Interval high = ts.ceiling(i);
if(low!=null && high!=null && low.end==i.start-1 && high.start==i.end+1){
i.start = low.start;
i.end = high.end;
ts.remove(low);
ts.remove(high);
ts.add(i);
} else if(high!=null && high.start==i.end+1){
high.start = i.start;
} else if(low!=null && low.end>=i.start-1){
low.end = Math.max(low.end, i.end);
} else {
ts.add(i);
}
}
public List<Interval> getIntervals() {
return new ArrayList<Interval>(ts);
}
}
/**
* Your SummaryRanges object will be instantiated and called as such:
* SummaryRanges obj = new SummaryRanges();
* obj.addNum(val);
* List<Interval> param_2 = obj.getIntervals();
*/