Leetcode•Jul 02, 2026

Merge Intervals

Hazrat Ali

Leetcode

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.

Example 3:

Input: intervals = [[4,7],[1,4]]
Output: [[1,7]]
Explanation: Intervals [1,4] and [4,7] are considered overlapping.

Solution
/**
 * @param {number[][]} intervals
 * @return {number[][]}
 */
var merge = function(intervals) {
    if (intervals.length === 0) return [];

    intervals.sort((a, b) => a[0] - b[0]);

    const result = [];
    let current = intervals[0];

    for (let i = 1; i < intervals.length; i++) {
        if (intervals[i][0] <= current[1]) {
           
            current[1] = Math.max(current[1], intervals[i][1]);
        } else {
            result.push(current);
            current = intervals[i];
        }
    }

    result.push(current);

    return result;
};
 

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