day 11 done!

11/ex2.py

@@ -0,0 +1,58 @@
+from collections import deque
+
+START = 'svr'
+END = 'out'
+
+def dfs_sort(graph): 
+    visited = set()
+    order = deque()
+
+    def dfs_helper(node):
+        visited.add(node)
+        for v in graph.get(node, []):
+            if v not in visited:
+                dfs_helper(v)
+        
+        order.appendleft(node)
+    
+    dfs_helper(START)
+    return order
+
+def dp(graph, order, start_i, end_is):
+    dp = {node: 0 for node in graph}
+    dp[start_i] = 1
+
+    for node in order:
+        for neighbor in graph[node]:
+            dp[neighbor] += dp[node]
+    
+    return [dp[end_i] for end_i in end_is]
+
+with open('input.txt', 'r') as file:
+    lines = file.readlines()
+
+graph = {}
+for line in lines:
+    line = line.strip()
+    nodes = line.split()
+    node = nodes[0].rstrip(':')
+    edges = nodes[1:]
+    graph[node] = edges
+
+graph[END] = []
+
+topological_order = dfs_sort(graph)
+
+print(topological_order)
+
+pruned_graph = {node: graph[node] for node in topological_order if node in graph}
+
+# Path combinations: svr->fft->dac->out and svr->dac->fft->out
+
+svr_fft, svr_dac = dp(pruned_graph, topological_order, START, ['fft', 'dac'])
+fft_out, fft_dac = dp(pruned_graph, topological_order, 'fft', [END, 'dac'])
+dac_fft, dac_out = dp(pruned_graph, topological_order, 'dac', ['fft', END])
+
+result = (svr_fft * fft_dac * dac_out) + (svr_dac * dac_fft * fft_out)
+
+print(result)