Insert Interval

Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).

You may assume that the intervals were initially sorted according to their start times.

Example 1:
Given intervals [1,3],[6,9], insert and merge [2,5] in as [1,5],[6,9].

Example 2:
Given [1,2],[3,5],[6,7],[8,10],[12,16], insert and merge [4,9] in as [1,2],[3,10],[12,16].

This is because the new interval [4,9] overlaps with [3,5],[6,7],[8,10].

注意更新的时候只更新newInterval，然后最后再插进去就行了。 因为顺序无所谓。

/**
 * 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 Solution {
    public ArrayList<Interval> insert(ArrayList<Interval> intervals, Interval newInterval) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        ArrayList<Interval> results = new ArrayList<Interval>();
        boolean sig = false;
        for(int i = 0; i < intervals.size(); i ++)
        {
            if(intervals.get(i).end < newInterval.start)
            {
                results.add(intervals.get(i));    
            }
            else
            {
                newInterval.start = Math.min(newInterval.start, intervals.get(i).start);
            }
            if(intervals.get(i).start > newInterval.end)
            {
                if(!sig)
                {
                    results.add(newInterval);
                    sig = true;
                }
                results.add(intervals.get(i));
            }
            else
            {
                newInterval.end = Math.max(newInterval.end, intervals.get(i).end);
            }
        }
        if(!sig)
        {
            results.add(newInterval);
        }
        return results;
    }
}

第二遍：

不使用额外的存储空间：

public class Solution {
    public ArrayList<Interval> insert(ArrayList<Interval> intervals, Interval newInterval) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(intervals == null || intervals.size() == 0){
            ArrayList<Interval> result = new ArrayList<Interval>(newInterval);
            result.add(newInterval); 
            return result;
        }
        for(int i = 0; i < intervals.size(); i ++){
            if(i == 0)
        }
        intervals.get(0).start = intervals.get(0).start > newInterval.start ?  newInterval.start : intervals.get(0).start;
        pq.add(newInterval);
        result.add(pq.poll());//poll out the minimum element in the queue
        int max_end = result.get(0).end;
        while(pq.size() != 0){
            Interval tmp = pq.poll();
            if(tmp.start <= max_end){
                max_end = max_end > tmp.end ? max_end : tmp.end;
                result.get(result.size() - 1).end = max_end;
            }else{
                result.add(tmp);
                max_end = tmp.end;
            }
        }
        return result;
    }
}