Merge Triplets to Form Target Triplet

Problem

Given a list of triplets and a target triplet, determine whether you can choose a subset of the triplets and merge them — taking the elementwise maximum across all chosen triplets — to form exactly the target triplet. A triplet is only safe to use if none of its values exceed the corresponding target value.

Examples

Example 1

Input:triplets = [[2,5,3],[1,8,4],[1,7,5]], target = [2,7,5]

Output:true

Constraints

1 <= triplets.length <= 10^5

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How to approach it: the Greedy pattern

Make the choice that looks best right now, without reconsidering it later, and trust that a sequence of locally optimal choices adds up to a globally optimal answer. It only works when the problem actually has that property.

Look for this pattern when

Sorting the input by some key, then making one pass with simple local decisions, intuitively seems to produce the best answer.
The problem involves intervals, scheduling, or resource allocation where "always take the best available option" tends to work.

Read the full Greedy guide →

Video walkthroughs

Original problem on LeetCode ↗