#313 Merge Intervals

Given an array of intervals where intervals[i] = [start_i, end_i], merge all overlapping intervals.

Rules:

• Merge any intervals that overlap
• Return array of non-overlapping intervals
• Result covers all input intervals
• Result can be in any order

Constraints:

• 1 ≤ intervals.length ≤ 1000
• intervals[i].length == 2
• 0 ≤ start ≤ end ≤ 1000

Examples:

// Example 1:
console.log(
  merge([
    [1, 3],
    [1, 5],
    [6, 7],
  ]),
);
// Output: [[1,5],[6,7]]
// Explanation: First two intervals overlap

// Example 2:
console.log(
  merge([
    [1, 2],
    [2, 3],
  ]),
);
// Output: [[1,3]]
// Explanation: Adjacent intervals merge