Leetcode56 Merge Intervals

Posted 2022-12-06 xuweimdm

Merge Intervals

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].

Solution

• 将所有的interval按照起点进行排序，然后合并。在判断两个interval是否可以合并的时候，只需要判断第一个interval的末端是否超过了第二个interval的起点即可。

public class Solution 
    public List<Interval> merge(List<Interval> intervals) 
        if(intervals.size()<=1)  return intervals;
        List<Interval> result = new ArrayList<Interval>();
        Collections.sort(intervals,new Comparator<Interval>()
            public int compare(Interval it1, Interval it2)
                return it1.start - it2.start;
            
        );
        Interval it1 = intervals.get(0);
        result.add(it1);
        for(int i=1;i<intervals.size();i++)
            Interval it2 = intervals.get(i);
            if(it1.end>=it2.start) it1.end = Math.max(it1.end,it2.end);
            else
                it1 = it2;
                result.add(it1);
            
        
        return result;