Problem Statement

Given a collection of pairs where each pair contains two elements [a, b] and a < b, find the maximum length of a chain you can form using pairs.

A pair [a, b] can follow another pair [c, d] in the chain if b < c.

You can select pairs in any order and don't need to use all the given pairs.

Examples

1. Example 1:

   • Input: [[1,2], [3,4], [2,3]]
   • Expected Output: 2
   • Justification: The longest chain is [1,2] -> [3,4]. The chain [1,2] -> [2,3] is invalid because 2 is not smaller than 2.

2. Example 2:

   • Input: [[5,6], [1,2], [8,9], [2,3]]
   • Expected Output: 3
   • Justification: The chain can be [1,2] -> [5,6] -> [8,9] or [2,3] -> [5,6] -> [8, 9].

3. Example 3:

   • Input: [[7,8], [5,6], [1,2], [3,5], [4,5], [2,3]]
   • Expected Output: 3
   • Justification: The longest possible chain is formed by chaining [1,2] -> [3,5] -> [7,8].

Constraints:

• n == pairs.length
• 1 <= n <= 1000
• -1000 <= left_i < right_i <= 1000

Try it yourself

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