require_relative 'util'

# --- Day 22: Grid Computing ---

# You gain access to a massive storage cluster arranged in a grid;
# each storage node is only connected to the four nodes directly
# adjacent to it (three if the node is on an edge, two if it's in a
# corner).

# You can directly access data only on node /dev/grid/node-x0-y0, but
# you can perform some limited actions on the other nodes:

# - You can get the disk usage of all nodes (via df). The result of
#   doing this is in your puzzle input.
# - You can instruct a node to move (not copy) all of its data to an
#   adjacent node (if the destination node has enough space to receive
#   the data). The sending node is left empty after this operation.

# Nodes are named by their position: the node named node-x10-y10 is
# adjacent to nodes node-x9-y10, node-x11-y10, node-x10-y9, and
# node-x10-y11.

# Before you begin, you need to understand the arrangement of data on
# these nodes. Even though you can only move data between directly
# connected nodes, you're going to need to rearrange a lot of the data
# to get access to the data you need. Therefore, you need to work out
# how you might be able to shift data around.

# To do this, you'd like to count the number of viable pairs of
# nodes. A viable pair is any two nodes (A,B), regardless of whether
# they are directly connected, such that:

# - Node A is not empty (its Used is not zero).
# - Nodes A and B are not the same node.
# - The data on node A (its Used) would fit on node B (its Avail).

# How many viable pairs of nodes are there?