Greedy Algorithms - Minimum Domino Rotations
Given two arrays representing the top and bottom halves of dominoes, which strategy is most effective to determine the minimum rotations needed to make all values in one row identical?
Given two arrays representing the top and bottom halves of dominoes, which strategy is most effective to determine the minimum rotations needed to make all values in one row identical?
easy💻 Programming Q1 of Q15
Step-by-Step Solution
Solution:
Step 1: Identify candidates from the first domino
Check the two values on the first domino as potential uniform values.Step 2: Count rotations for each candidate
For each candidate, count how many rotations are needed to make all elements in either top or bottom equal to that candidate.Step 3: Determine minimal rotations
The minimum rotations among candidates is the answer, or -1 if impossible. This is a greedy approach.Final Answer:
Option C -> Option CQuick Check:
Only two candidates need checking, making it efficient. [OK]
Quick Trick: Check only first domino values as candidates [OK]
Common Mistakes:
MISTAKES- Trying all numbers 1-6 unnecessarily
- Using DP or backtracking leading to inefficiency
- Ignoring the possibility that no uniform row exists
Trap Explanation:
PITFALL- Other approaches seem plausible but are inefficient or unnecessary.
Interviewer Note:
CONTEXT- Tests understanding of problem-solving patterns and greedy strategy.
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