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Grokking the Coding Interview Patterns in C#

Solution: The K Weakest Rows in a Matrix

Understand how to find the k weakest rows in an m by n binary matrix by applying a modified binary search to count soldiers in each row. Learn to use a max-heap to track and retrieve the weakest rows efficiently, balancing time and space complexity for optimal solutions.

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Statement

You are given an m×nm \times n binary matrix of 11’s (representing soldiers) and 00’s (representing civilians). The soldiers are positioned in front of the civilians, i.e., all the 11’s will appear to the left of all the 00’s in each row.

A row ii is weaker than a row jj if any of the following is TRUE:

  • The number of soldiers in row ii is less than the number of soldiers in row jj.

  • Both rows have the same number of soldiers and  ...