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Grokking the Coding Interview Patterns in Go

Solution: Minimum Moves to Spread Stones Over Grid

Understand how to apply backtracking techniques to distribute stones across a 3x3 grid with exactly one stone per cell. This lesson guides you through identifying empty and extra stone cells, calculating moves with Manhattan distance, and exploring all placements to find the minimum moves required.

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 ...