56. Merge Intervals

🟠   🔖  数组 排序  🔗 LeetCode

题目

Given an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cover all the intervals in the input.

Example 1:

Input: intervals = [[1,3],[2,6],[8,10],[15,18]]

Output: [[1,6],[8,10],[15,18]]

Explanation: Since intervals [1,3] and [2,6] overlap, merge them into [1,6].

Example 2:

Input: intervals = [[1,4],[4,5]]

Output: [[1,5]]

Explanation: Intervals [1,4] and [4,5] are considered overlapping.

Constraints:

• 1 <= intervals.length <= 10^4
• intervals[i].length == 2
• 0 <= starti <= endi <= 10^4

题目大意

以数组 intervals 表示若干个区间的集合，其中单个区间为 intervals[i] = [starti, endi] 。请你合并所有重叠的区间，并返回 一个不重叠的区间数组，该数组需恰好覆盖输入中的所有区间 。

解题思路

• 一个区间可以表示为 [start, end]，先按区间的 start 排序
• 对于几个相交区间合并后的结果区间 x，x.start 一定是这些相交区间中 start 最小的，x.end 一定是这些相交区间中 end 最大的
• 由于已经排了序，x.start 很好确定，求 x.end 也很容易，可以类比在数组中找最大值的过程。

代码

/**
 * @param {number[][]} intervals
 * @return {number[][]}
 */
var merge = function (intervals) {
	let res = [];

	// 先按区间的 `start` 排序
	intervals = intervals.sort((a, b) => a[0] - b[0]);
	for (let i = 0; i < intervals.length; i++) {
		let start = intervals[i][0],
			end = intervals[i][1];

		// 如果区间相交，求结果区间 [start, end]
		while (intervals[i + 1] && inRange(intervals[i + 1], start, end)) {
			start = Math.min(start, intervals[i + 1][0]);
			end = Math.max(end, intervals[i + 1][1]);
			i++;
		}
		res.push([start, end]);
	}
	return res;
};

// 判断区间是否相交
var inRange = function (interval, start, end) {
	let [m, n] = interval;
	if (m < start && n < start) return false;
	if (m > end && n > end) return false;
	return true;
};

相关题目

相关题目

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- [57. 插入区间](https://leetcode.com/problems/insert-interval)
- [🔒 Meeting Rooms](https://leetcode.com/problems/meeting-rooms)
- [🔒 Meeting Rooms II](https://leetcode.com/problems/meeting-rooms-ii)
- [495. 提莫攻击](https://leetcode.com/problems/teemo-attacking)
- [🔒 Add Bold Tag in String](https://leetcode.com/problems/add-bold-tag-in-string)
- [715. Range 模块](https://leetcode.com/problems/range-module)
- [🔒 Employee Free Time](https://leetcode.com/problems/employee-free-time)
- [763. 划分字母区间](https://leetcode.com/problems/partition-labels)
- [986. 区间列表的交集](https://leetcode.com/problems/interval-list-intersections)
- [🔒 Amount of New Area Painted Each Day](https://leetcode.com/problems/amount-of-new-area-painted-each-day)
- [2213. 由单个字符重复的最长子字符串](https://leetcode.com/problems/longest-substring-of-one-repeating-character)
- [2276. 统计区间中的整数数目](https://leetcode.com/problems/count-integers-in-intervals)
- [2406. 将区间分为最少组数](https://leetcode.com/problems/divide-intervals-into-minimum-number-of-groups)
- [2446. 判断两个事件是否存在冲突](https://leetcode.com/problems/determine-if-two-events-have-conflict)
- [2580. 统计将重叠区间合并成组的方案数](https://leetcode.com/problems/count-ways-to-group-overlapping-ranges)
- [2848. Points That Intersect With Cars](https://leetcode.com/problems/points-that-intersect-with-cars)