leetcode -- 57. Insert Interval

题目描述

题目难度：Hard
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].

AC代码

/**
 * 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; }
 * }
 */
class Solution {
   public List<Interval> insert(List<Interval> intervals, Interval newInterval) {
    List<Interval> result = new LinkedList<>();
    int i = 0;
    // add all the intervals ending before newInterval starts
    while (i < intervals.size() && intervals.get(i).end < newInterval.start)
        result.add(intervals.get(i++));
    // merge all overlapping intervals to one considering newInterval
    while (i < intervals.size() && intervals.get(i).start <= newInterval.end) {
        newInterval = new Interval( // we could mutate newInterval here also
                Math.min(newInterval.start, intervals.get(i).start),
                Math.max(newInterval.end, intervals.get(i).end));
        i++;
    }
    result.add(newInterval); // add the union of intervals we got
    // add all the rest
    while (i < intervals.size()) result.add(intervals.get(i++)); 
    return result;
}
}