Irrigation Planner

Problem Statement

Imagine you are tasked with planning the irrigation for a rectangular farmland represented by a 2D grid. Each cell in the grid can be in one of three states:

• 0: Dry soil that hasn't been watered yet.
• 1: A water source that immediately supplies water.
• -1: An obstacle (such as a rock) where neither water can pass through nor irrigation can occur.

Water from each water source flows to its adjacent cells (up, down, left, right) and takes one minute to move from one cell to an adjacent cell. Water can spread from the water source to neighboring cells (that contain dry soil) and then further spread from those cells, continuing every minute.

Your goal is to determine the minimum time required to irrigate all soil cells that can possibly receive water. If there is any cell with dry soil that never gets watered, return -1.

Input

• A 2D list (or array) of integers where each integer is one of {1, 0, -1} representing the farmland grid.

Output

• An integer representing the minimum number of minutes needed to irrigate all reachable dry soil cells, or -1 if some cells remain dry.

Examples

Example 1:

Input: [
  [0,  1,  0],
  [0, -1,  0],
  [0,  0,  0]
]

Output: 3

Example 2:

Input: [
  [0,  -1,  1],
  [0,  -1,  0],
  [0,   0,  0]
]

Output: -1

Constraints

• The dimensions of the grid are at least 1 x 1.
• The grid may not be rectangular in shape in some languages; in that case, assume you are given a list of lists where all inner lists are of equal length.

Implement a function or method to solve the problem based on the description above.