[LeetCode] Insert Interval

Problem

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:

Input: intervals = [[1,3],[6,9]], newInterval = [2,5]
Output: [[1,5],[6,9]]

Example 2:

Input: intervals = [[1,2],[3,5],[6,7],[8,10],[12,16]], newInterval = [4,8]
Output: [[1,2],[3,10],[12,16]]
Explanation: Because the new interval [4,8] overlaps with [3,5],[6,7],[8,10].

Solution

with new list

class Solution {
    public List<Interval> insert(List<Interval> intervals, Interval itvl) {
        List<Interval> res = new ArrayList<>();
        if (intervals == null || intervals.size() == 0) {
            intervals.add(itvl);
            return intervals;
        }
        int i = 0;
        while (i < intervals.size() && intervals.get(i).end < itvl.start) {
            res.add(intervals.get(i++));
        }
        while (i < intervals.size() && intervals.get(i).start <= itvl.end) {
            itvl.start = Math.min(intervals.get(i).start, itvl.start);
            itvl.end = Math.max(intervals.get(i).end, itvl.end);
            i++;
        }
        res.add(itvl);
        while (i < intervals.size()) {
            res.add(intervals.get(i++));
        }
        return res;
    }