Hand of Straights

Problem

Given a hand of cards and a group size, determine whether the cards can be rearranged into groups of that size where each group consists of consecutive values.

Examples

Example 1

Input:hand = [1,2,3,6,2,3,4,7,8], groupSize = 3

Output:true

Constraints

1 <= hand.length <= 10^4

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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.

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Video walkthroughs

Original problem on LeetCode ↗