111 lines
2.1 KiB
Python
111 lines
2.1 KiB
Python
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width = 10
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height = 10
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grid = {}
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with open("input.txt") as f:
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lines = f.read().split('\n')
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for i in range(height):
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for j in range(width):
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grid[(i,j)] = int(lines[i][j])
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def steps(grid, steps):
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"""
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Step through grid multiple times
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and count the flashes.
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"""
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flashes = 0
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for i in range(steps):
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flashes += step(grid)
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return flashes
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def step(grid):
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"""
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Step through grid once
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and count the flashes.
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"""
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increment(grid)
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flashes = flash(grid)
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return flashes
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def increment(grid):
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"""
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Increment the entire grid.
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"""
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for i in range(height):
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for j in range(width):
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grid[(i,j)] += 1
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def flash(grid):
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"""
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Calculate which octopi should flash.
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Also count how many flashes.
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"""
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flashes = 0
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flashed = set()
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cascade = []
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# find which octopi should flash and add them to queue
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for i in range(height):
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for j in range(width):
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point = (i,j)
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if grid[point] > 9 and point not in flashed:
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flashed.add(point)
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cascade += neighbors(point)
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grid[point] = 0 # reset
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flashes += 1
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# process the queue of flashing octopi
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while cascade:
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point = cascade.pop()
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# if it hasn't already flashed, increment its energy
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if point not in flashed:
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grid[point] = grid[point] + 1
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# then figure out if it should flash
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if grid[point] > 9 and point not in flashed:
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flashed.add(point)
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cascade += neighbors(point)
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grid[point] = 0 # reset
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flashes += 1
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return flashes
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def neighbors(point):
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"""
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Get a list of neighboring points,
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diagonals included.
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"""
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i,j = point
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n = [
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(i-1,j-1),
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(i-1,j),
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(i-1,j+1),
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(i,j-1),
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#(i,j) is excluded
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(i,j+1),
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(i+1,j-1),
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(i+1,j),
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(i+1,j+1)
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]
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return [ (i,j) for (i,j) in n if (-1 < i < height) and (-1 < j < width) ]
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def display(grid):
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"""
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Pretty print the grid.
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"""
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for i in range(height):
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row = []
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for j in range(width):
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row.append(grid[(i,j)])
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print(row)
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grid1 = grid.copy()
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part1 = steps(grid1,100)
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#display(grid1)
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print(part1)
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grid2 = grid.copy()
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from collections import Counter
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i = 0
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while True:
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step(grid2)
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i += 1
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c = Counter(grid2.values())
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if c[0] == width * height: # all are flashing at same time
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break
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print(i)
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