数组——merge-intervals

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题目描述：

Given a collection of intervals, merge all overlapping intervals.

For example,
Given[1,3],[2,6],[8,10],[15,18],
return[1,6],[8,10],[15,18].

/**
 * 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; }
 * }
 */
import java.util.*;
public class Solution {
	    public ArrayList<Interval> merge(ArrayList<Interval> intervals) {
	        ArrayList<Interval> array=new ArrayList();
	        if(intervals == null||intervals.size() == 0)
	            return array;
	        
	        Collections.sort(intervals,new intervalComparator());
	        int start=intervals.get(0).start;
	        int end=intervals.get(0).end;
	        for(int i=1;i<intervals.size();i++)
	            {
	            Interval inter=intervals.get(i);
	            if(inter.start>end)
	                {
	                array.add(new Interval(start,end));
	                start=inter.start;
	                end=inter.end;
	            }else
	                {
	                end=Math.max(end,inter.end);
	            }
	        }
	         array.add(new Interval(start,end));
	        return array;
	    }
	}
//外部实现比较器Comparator 泛型<Interval>;
class intervalComparator implements Comparator<Interval>
	    {
	    public int compare(Interval a,Interval b)
	        {
	         if(a.start!=b.start)
	             {
	             return a.start-b.start;
	         }else
	             {
	             return a.end-b.end;
	         }
	    }
	}