Java Insert Interval(插入间隔)

Problem:

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

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].

Thoughts of This Problem

Quickly summarize 3 cases. Whenever there is intersection, created a new interval.



Java 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 Solution {
public ArrayList<Interval> insert(ArrayList<Interval> intervals, Interval newInterval) {

ArrayList<Interval> result = new ArrayList<Interval>();

for(Interval interval: intervals){
if(interval.end < newInterval.start){
result.add(interval);
}else if(interval.start > newInterval.end){
result.add(newInterval);
newInterval = interval;
}else if(interval.end >= newInterval.start || interval.start <= newInterval.end){
newInterval = new Interval(Math.min(interval.start, newInterval.start), Math.max(newInterval.end, interval.end));
}
}

result.add(newInterval);

return result;
}
}