largest_number.py

#Uses python3

import sys
import itertools
from random import randrange

def largest_number(a):
    #write your code here
    def numCmp(a,b):
        '''
        :param a:
        :param b: a and b - strings of int
        :return: if a >= b: true else false
        '''
        acp,bcp = list(a),list(b)
        minlen = min(len(a),len(b))
        for i in range(minlen):
            topa= acp.pop(0)
            topb = bcp.pop(0)
            if int(topa) != int(topb): return int(topa) > int(topb)
        # return len(a)<=len(b)
        if acp==bcp==[]: return False
        if  acp==[]:
            try:
                while bcp[-1] == '0': bcp = bcp[:-1]
            except IndexError:
                return False
            for ll in bcp:
                if int(ll)<int(a[0]): return True
            return False
            #if int(''.join(bcp))> int(a[0]) and bcp[0]!='0': return False
            #else: return True
        if bcp==[]:
            try:
                while acp[-1] == '0': acp = acp[:-1]
            except IndexError:
                return False
            if acp == []: return False
            for ll in acp:
                if int(ll)<int(b[0]): return False
            return True
            # if int(''.join(acp))> int(b[0]) and acp[0]!='0': return True
            # else: return False

    def qsort(inlist):
        if inlist == []:
            return []
        else:
            pivot = inlist[0]
            lesser = qsort([x for x in inlist[1:] if numCmp(x,pivot)])
            greater = qsort([x for x in inlist[1:] if not(numCmp(x,pivot))])
            return lesser + [pivot] + greater

    return qsort(a)

def RandTest():
    for m in range(500):
        a = []
        for z in range(3):
            ran = randrange(0, 500)
            a.append(str(ran))
        # print(a)
        # print(largest_number(a))
        z = list(map(''.join, list(itertools.permutations(a))))
        z = max(list(map(int, z)))
        x = int(''.join(largest_number(a)))
        if x != z: print("Failure", x, z, a)
if __name__ == '__main__':
    # input = sys.stdin.read()
    input = '3 109 202 342 130 1'
    data = input.split()
    a = data[1:]
    # x = int(''.join(largest_number(a)))
    x = largest_number(a)
    RandTest()
    print(x)