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Grokking the Coding Interview Patterns in Python

Solution: Minimum Moves to Spread Stones Over Grid

Explore how to determine the minimum number of moves to place one stone in each cell of a 3x3 grid using backtracking. Understand the process of identifying empty and extra stone cells, calculating moves with Manhattan distance, and using recursion and backtracking to try all combinations for the optimal solution.

We'll cover the following...

Statement

Given a 2D grid of integers of size (3×33 \times 3), where each value represents the number of stones in the given cell, return the minimum number of moves required to place exactly one stone in each grid cell.

Constraints:

  • Only one stone can be moved in one move.

  • Stone from a cell can only be moved to another cell if they are adjacent (share a side).

  • The sum of all stones in the grid must be equal to 99.

  • grid.length, grid[i].length ...