#127 Medium Time O(n) Space O(1) Animated

Merge Triplets to Form Target Triplet

Check if target triplet can be formed by merging valid triplets.

LeetCode ↗

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1 Predict
2 Trace
3 Explain
4 Implement

Pattern Greedy choice with a local proof

Commit to the locally best safe choice only after identifying why it cannot block an optimal answer.

Approach: Greedy

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Core Insight

Commit to the locally best safe choice only after identifying why it cannot block an optimal answer.

Common Pitfall

Sort or define the selection order before applying the greedy rule.

Description

Check if target triplet can be formed by merging valid triplets.

Constraints

Time Complexity: O(n)
Space Complexity: O(1)

Solution — Greedy

TimeO(n) SpaceO(1)

Implementation Plan

Translate the invariant into these small, testable moves.

Order candidates by the greedy criterion.
Inspect the next candidate.
Accept it only when it preserves feasibility.
Return the accumulated result.

def mergeTriplets(triplets, target):
    good = set()
    
    for t in triplets:
        if t[0] > target[0] or t[1] > target[1] or t[2] > target[2]:
            continue
        for i, v in enumerate(t):
            if v == target[i]:
                good.add(i)
                
    return len(good) == 3

Hand of Straights

Partition Labels

Merge Triplets to Form Target Triplet

Steps

Description

Constraints

Tags

Solution — Greedy