breadth first traversal

bfirsttrav.py

#!/usr/bin/python

def getLinks(url):
    pass

#### SOL 1

def handleLinks(links , seen , out):
    nextLayer = []
    for link in links:
        if link in seen:
            continue
        print >> out , link
        seen.add(link)
        nextLayer.extend(getLinks(link))
    if len(nextLayer) > 0:
        return handleLinks(nextLayer , seen , out)

start = 'http://example.com'
seen = set()
initLinks = getLinks(start)
outfile = '/var/tmp/out'
fh = open(outfile , 'w')
handleLinks(initLinks , seen , out)
fh.close()

#### SOL 2

from collections import deque


start = 'http://example.com'
seen = set()
q = deque()
q.extend(getLinks(start))

outfile = '/var/tmp/out'
fh = open(outfile , 'w')
while q:
    link = q.popleft()
    if link in seen:
        continue
    seen.add(link)
    print >> fh , link
    q.extend(getLinks(link))
fh.close()