56. Merge Intervals

Problem

Tags: Array, Sorting

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

Code

JS

// 56. Merge Intervals (1/31/53841)
// Runtime: 84 ms (94.59%) Memory: 41.56 MB (94.81%) 

/**
 * @param {number[][]} intervals
 * @return {number[][]}
 */
function merge(intervals) {
    intervals.sort((a,b) => a[1] - b[1]);
    
    for(let i = intervals.length - 2; i >= 0; i--) {
        if(intervals[i][1] >= intervals[i + 1][0]) {
            const prev = intervals.splice(i + 1, 1)[0];
            intervals[i] = [ Math.min(intervals[i][0], prev[0]), Math.max(intervals[i][1], prev[1]) ];
        }
    }
    
    return intervals;
};