Hand of Straights
Detailed guide and Python implementation for the 'Hand of Straights' problem.
1. Concept Overview
The 'Hand of Straights' problem is a key challenge in the Greedy section.
This implementation focuses on easy-level logic in Python.
We prioritize technical accuracy and code readability in our provided solutions.
2. Real-World Applications
3. Visual Intuition
Visualizing the logic flow for Hand of Straights.
4. Prerequisites
5. Step-by-Step Thinking
1. Understand the problem
Read the problem statement for Hand of Straights carefully.
2. Formulate brute force
Draft a simple iterative solution.
3. Identify inefficiency
Look for redundant calculations.
4. Optimize search path
Use hashing or sorting to speed up the process.
5. Final Implementation
Clean up the code for production standards.
Problem Statement
Alice has some number of cards and she wants to rearrange the cards into groups so that each group is of size groupSize, and consists of groupSize consecutive cards. Given an integer array hand where hand[i] is the value written on the ith card and an integer groupSize, return True if she can rearrange the cards, or False otherwise.
Write a function isNStraightHand(hand: List[int], groupSize: int) -> bool.
- •1 <= len(hand) <= 10^4
- •0 <= hand[i] <= 10^9
- •1 <= groupSize <= len(hand)
Examples
hand = [1,2,3,6,2,3,4,7,8], groupSize = 3
True
[1,2,3], [2,3,4], [6,7,8] are consecutive groups of 3.
hand = [1,2,3,4,5], groupSize = 4
False
Cannot rearrange cards into consecutive groups of 4.
Need a Hint?
Edge Cases to Watch
- Empty input structures
- Single element inputs
- Large numerical bounds
Ready to Solve?
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Interview Insights & Variations
Complexity Analysis Breakdown
Why Time: Directly evaluates all possibilities.
Why Space: Uses standard local memory.
Why Time: Optimized paths reduce total operations.
Why Space: May trade memory for speed.
Optimized Solution Python Code
Optimized Solution Python Code
import heapq, collections
def is_n_straight_hand_opt(hand, groupSize):
if len(hand) % groupSize: return False
count = collections.Counter(hand)
minH = list(count.keys()); heapq.heapify(minH)
while minH:
first = minH[0]
for i in range(first, first + groupSize):
if i not in count: return False
count[i] -= 1
if count[i] == 0:
if i != minH[0]: return False
heapq.heappop(minH)
return TrueBrute Force Code (Spoiler Guarded)
Brute Force Code (Spoiler Guarded)
def is_n_straight_hand_brute(hand, groupSize):
if len(hand) % groupSize: return False
hand.sort()
while hand:
first = hand.pop(0)
for i in range(1, groupSize):
if (first + i) not in hand: return False
hand.remove(first + i)
return TrueAlgorithm Pattern Checklist
When dealing with Greedy data patterns.
Core Prerequisites
Revision Key Notes
Common Mistakes & Pitfalls
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