Prinsessejakt

from sys import stdindef subgraftetthet(nabomatrise, startnode):    n = len(nabomatrise)    besokt = [False] * n    besok(nabomatrise, startnode, besokt)        noder = 0    kanter = 0        for node in range(0, n):        if besokt[node] == False:            noder += 1            for nabonode in range(0, n):                if nabomatrise[node][nabonode] == True and besokt[nabonode] == False:                    kanter += 1        if noder == 0:        return 0.0    else:        return float(kanter) / float(noder**2)    def besok(nabomatrise, node, besokt):    besokt[node] = True    for nabonode in range(0, len(nabomatrise)):        if nabomatrise[node][nabonode] == True and besokt[nabonode] == False:            besok(nabomatrise, nabonode, besokt)def main():    n = int(stdin.readline())    nabomatrise = [None] * n # rader    for i in range(0, n):        nabomatrise[i] = [False] * n # kolonner        linje = stdin.readline()        for j in range(0, n):            nabomatrise[i][j] = (linje[j] == '1')    for linje in stdin:        start = int(linje)        print "%.3f" % (subgraftetthet(nabomatrise, start) + 1E-12)main()