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S.Çağlar Onura95895d2015-02-09 13:34:11 -05001#!/usr/bin/env python
Sapan Bhatia26d40bc2014-05-12 15:28:02 -04002
3import time
4import traceback
5import commands
6import threading
7import json
8import pdb
9
10from datetime import datetime
11from collections import defaultdict
12
Sapan Bhatiab1d8a0f2014-09-01 17:41:19 -040013# Assumes that there are no empty dependencies
14# in the graph. E.g. Foo -> []
15def dfs(graph, visit):
16 nodes = graph.keys()
17 edge_nodes = set()
18
19 for n in nodes:
20 edge_nodes|=set(graph[n])
21
Sapan Bhatiab1d8a0f2014-09-01 17:41:19 -040022 sinks = list(edge_nodes - set(nodes))
23 sources = list(set(nodes) - edge_nodes)
24
Sapan Bhatiab1d8a0f2014-09-01 17:41:19 -040025 nodes.extend(sinks)
26
Sapan Bhatiab1d8a0f2014-09-01 17:41:19 -040027 visited = set(sources)
28 stack = sources
29 while stack:
30 current = stack.pop()
31 visit(current)
32 for node in graph[current]:
33 if node not in visited:
34 stack.append(node)
35 visited.add(node)
36
Sapan Bhatia119ef902014-09-03 01:07:10 -040037 return sources
Sapan Bhatiab1d8a0f2014-09-01 17:41:19 -040038
Sapan Bhatia26d40bc2014-05-12 15:28:02 -040039# Topological sort
40# Notes:
41# - Uses a stack instead of recursion
42# - Forfeits optimization involving tracking currently visited nodes
43def toposort(g, steps=None):
44 # Get set of all nodes, including those without outgoing edges
45 keys = set(g.keys())
46 values = set({})
47 for v in g.values():
48 values=values | set(v)
49
50 all_nodes=list(keys|values)
51 if (not steps):
52 steps = all_nodes
53
54 # Final order
55 order = []
56
57 # DFS stack, not using recursion
58 stack = []
59
60 # Unmarked set
61 unmarked = all_nodes
62
63 # visiting = [] - skip, don't expect 1000s of nodes, |E|/|V| is small
64
65 while unmarked:
66 stack.insert(0,unmarked[0]) # push first unmarked
67
68 while (stack):
69 n = stack[0]
70 add = True
71 try:
72 for m in g[n]:
73 if (m in unmarked):
74 if (m not in stack):
75 add = False
76 stack.insert(0,m)
77 else:
78 # Should not happen, if so there's a loop
79 print 'Loop at %s'%m
80 except KeyError:
81 pass
82 if (add):
83 if (n in steps):
84 order.append(n)
85 item = stack.pop(0)
86 unmarked.remove(item)
87
88 noorder = list(set(steps) - set(order))
89 return order + noorder
90
91def main():
92 graph_file=open('planetstack.deps').read()
93 g = json.loads(graph_file)
94 print toposort(g)
95
96if (__name__=='__main__'):
97 main()
98
99#print toposort({'a':'b','b':'c','c':'d','d':'c'},['d','c','b','a'])