【LeetCode】57. Insert Interval

1.题目描述

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.

给出一个无重叠的 ，按照区间起始端点排序的区间列表。

在列表中插入一个新的区间，你需要确保列表中的区间仍然有序且不重叠（如果有必要的话，可以合并区间）。

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].

2.Solutions

Here’s a pretty straight-forward and concise solution below.

public static int[][] insert(int[][] intervals, int[] newInterval) {
    List<int[]> result = new LinkedList<>();
    int i = 0;
    // add all the intervals ending before newInterval starts
    while (i < intervals.length && intervals[i][1] < newInterval[0]){
        result.add(intervals[i]);
        i++;
    }

    // merge all overlapping intervals to one considering newInterval
    while (i < intervals.length && intervals[i][0] <= newInterval[1]) {
        // we could mutate newInterval here also
        newInterval[0] = Math.min(newInterval[0], intervals[i][0]);
        newInterval[1] = Math.max(newInterval[1], intervals[i][1]);
        i++;
    }

    // add the union of intervals we got
    result.add(newInterval); 

    // add all the rest
    while (i < intervals.length){
        result.add(intervals[i]); 
        i++;
    }

    return result.toArray(new int[result.size()][]);
}

（完）