59 lines
1.3 KiB
Python
59 lines
1.3 KiB
Python
from collections import deque
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START = 'svr'
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END = 'out'
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def dfs_sort(graph):
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visited = set()
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order = deque()
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def dfs_helper(node):
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visited.add(node)
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for v in graph.get(node, []):
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if v not in visited:
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dfs_helper(v)
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order.appendleft(node)
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dfs_helper(START)
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return order
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def dp(graph, order, start_i, end_is):
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dp = {node: 0 for node in graph}
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dp[start_i] = 1
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for node in order:
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for neighbor in graph[node]:
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dp[neighbor] += dp[node]
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return [dp[end_i] for end_i in end_is]
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with open('input.txt', 'r') as file:
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lines = file.readlines()
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graph = {}
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for line in lines:
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line = line.strip()
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nodes = line.split()
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node = nodes[0].rstrip(':')
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edges = nodes[1:]
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graph[node] = edges
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graph[END] = []
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topological_order = dfs_sort(graph)
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print(topological_order)
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pruned_graph = {node: graph[node] for node in topological_order if node in graph}
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# Path combinations: svr->fft->dac->out and svr->dac->fft->out
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svr_fft, svr_dac = dp(pruned_graph, topological_order, START, ['fft', 'dac'])
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fft_out, fft_dac = dp(pruned_graph, topological_order, 'fft', [END, 'dac'])
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dac_fft, dac_out = dp(pruned_graph, topological_order, 'dac', ['fft', END])
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result = (svr_fft * fft_dac * dac_out) + (svr_dac * dac_fft * fft_out)
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print(result)
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