Project Euler #13 in Python, trying to find smart solution

Question

I'm trying to solve problem 13 from Euler project, and I'm trying to make the solution beautiful (at least, not ugly). Only "ugly thing" I do is that I'm pre-formating the input and keep it in the solution file (due to some technical reasons, and 'cause I want to concentrate on numeric part of problem) The problem is "Work out the first ten digits of the sum of the following one-hundred 50-digit numbers." I wrote some code, that should work, as far as I know, but it gives wrong result. I've checked input several times, it seems to be OK...

nums=[37107287533902102798797998220837590246510135740250,
46376937677490009712648124896970078050417018260538,
74324986199524741059474233309513058123726617309629,
91942213363574161572522430563301811072406154908250,
23067588207539346171171980310421047513778063246676,
89261670696623633820136378418383684178734361726757,
28112879812849979408065481931592621691275889832738,
44274228917432520321923589422876796487670272189318,
47451445736001306439091167216856844588711603153276,
70386486105843025439939619828917593665686757934951,
62176457141856560629502157223196586755079324193331,
64906352462741904929101432445813822663347944758178,
92575867718337217661963751590579239728245598838407,
58203565325359399008402633568948830189458628227828,
80181199384826282014278194139940567587151170094390,
35398664372827112653829987240784473053190104293586,
86515506006295864861532075273371959191420517255829,
71693888707715466499115593487603532921714970056938,
54370070576826684624621495650076471787294438377604,
53282654108756828443191190634694037855217779295145,
36123272525000296071075082563815656710885258350721,
45876576172410976447339110607218265236877223636045,
17423706905851860660448207621209813287860733969412,
81142660418086830619328460811191061556940512689692,
51934325451728388641918047049293215058642563049483,
62467221648435076201727918039944693004732956340691,
15732444386908125794514089057706229429197107928209,
55037687525678773091862540744969844508330393682126,
18336384825330154686196124348767681297534375946515,
80386287592878490201521685554828717201219257766954,
78182833757993103614740356856449095527097864797581,
16726320100436897842553539920931837441497806860984,
48403098129077791799088218795327364475675590848030,
87086987551392711854517078544161852424320693150332,
59959406895756536782107074926966537676326235447210,
69793950679652694742597709739166693763042633987085,
41052684708299085211399427365734116182760315001271,
65378607361501080857009149939512557028198746004375,
35829035317434717326932123578154982629742552737307,
94953759765105305946966067683156574377167401875275,
88902802571733229619176668713819931811048770190271,
25267680276078003013678680992525463401061632866526,
36270218540497705585629946580636237993140746255962,
24074486908231174977792365466257246923322810917141,
91430288197103288597806669760892938638285025333403,
34413065578016127815921815005561868836468420090470,
23053081172816430487623791969842487255036638784583,
11487696932154902810424020138335124462181441773470,
63783299490636259666498587618221225225512486764533,
67720186971698544312419572409913959008952310058822,
95548255300263520781532296796249481641953868218774,
76085327132285723110424803456124867697064507995236,
37774242535411291684276865538926205024910326572967,
23701913275725675285653248258265463092207058596522,
29798860272258331913126375147341994889534765745501,
18495701454879288984856827726077713721403798879715,
38298203783031473527721580348144513491373226651381,
34829543829199918180278916522431027392251122869539,
40957953066405232632538044100059654939159879593635,
29746152185502371307642255121183693803580388584903,
41698116222072977186158236678424689157993532961922,
62467957194401269043877107275048102390895523597457,
23189706772547915061505504953922979530901129967519,
86188088225875314529584099251203829009407770775672,
11306739708304724483816533873502340845647058077308,
82959174767140363198008187129011875491310547126581,
97623331044818386269515456334926366572897563400500,
42846280183517070527831839425882145521227251250327,
55121603546981200581762165212827652751691296897789,
32238195734329339946437501907836945765883352399886,
75506164965184775180738168837861091527357929701337,
62177842752192623401942399639168044983993173312731,
32924185707147349566916674687634660915035914677504,
99518671430235219628894890102423325116913619626622,
73267460800591547471830798392868535206946944540724,
76841822524674417161514036427982273348055556214818,
97142617910342598647204516893989422179826088076852,
87783646182799346313767754307809363333018982642090,
10848802521674670883215120185883543223812876952786,
71329612474782464538636993009049310363619763878039,
62184073572399794223406235393808339651327408011116,
66627891981488087797941876876144230030984490851411,
60661826293682836764744779239180335110989069790714,
85786944089552990653640447425576083659976645795096,
66024396409905389607120198219976047599490197230297,
64913982680032973156037120041377903785566085089252,
16730939319872750275468906903707539413042652315011,
94809377245048795150954100921645863754710598436791,
78639167021187492431995700641917969777599028300699,
15368713711936614952811305876380278410754449733078,
40789923115535562561142322423255033685442488917353,
44889911501440648020369068063960672322193204149535,
41503128880339536053299340368006977710650566631954,
81234880673210146739058568557934581403627822703280,
82616570773948327592232845941706525094512325230608,
22918802058777319719839450180888072429661980811197,
77158542502016545090413245809786882778948721859617,
72107838435069186155435662884062257473692284509516,
20849603980134001723930671666823555245252804609722,
53503534226472524250874054075591789781264330331690]
result_sum = []
tmp_sum = 0
for j in xrange(50):
    for i in xrange(100):
        tmp_sum += nums[i] % 10
        nums[i] =nums[i] / 10
    result_sum.insert(0,int(tmp_sum % 10))
    tmp_sum = tmp_sum / 10
for i in xrange(10):
    print result_sum[i]

Answer 1

As Simple as this :

Values.txt will contain all digits.

nums = []

with open("values.txt",'r') as f:
    for num in f:
        nums.append(int(num))

print(str(sum(nums))[:10])

Answer 2

Just as easy is storing it in csv and using pandas:

def foo():
    import pandas as pd 
    table = pd.read_csv("data.txt", header = None, usecols = [0]) 

and then iterate through panda dataframe:

    sum = 0 
    for x in range(len(table)):
        sum += int(table[0][x])

    return str(sum)[:10]

just keep in mind that Python handles the large digits for you.

Answer 3

You could save the numbers in a file (with a number on each line), and read from it:

nums = []
with open('numbers.txt', 'r') as f:
    for num in f:
        nums.append(int(num))

# nums is now populated with all of the numbers, so do your actual algorithm

Also, it looks like you want to store the sum as an array of digits. The cool thing about Python is that it automatically handles large integers. Here is a quote from the docs:

Plain integers (also just called integers) are implemented using long in C, which gives them at least 32 bits of precision (sys.maxint is always set to the maximum plain integer value for the current platform, the minimum value is -sys.maxint - 1). Long integers have unlimited precision.

So using an array of digits isn't really necessary if you are working with Python. In C, it is another story...

Also, regarding your code, you need to factor in the digits in tmp_sum, which contains your carry-over digits. You can add them into result_sum like this:

while tmp_sum:
    result_sum.insert(0,int(tmp_sum % 10))
    tmp_sum /= 10

This will fix your issue. Here, it works.

Answer 4

Your code works by adding all the numbers in nums like a person would: adding column by column. Your code does not work because when you are summing the far left column, you treat it like every other column. Whenever people get to the far left, they write down the entire sum. So this line

result_sum.insert(0,int(tmp_sum % 10))

doesn't work for the far left column; you need to insert something else into result_sum in that case. I would post the code, but 1) I'm sure you don't need it, and 2) it's agains the Project-Euler tag rules. If you would like, I can email it to you, but I'm sure that won't be necessary.

Answer 5

Since you already have all the numbers in a list, you should be able to take the sum of them pretty easily. Then you just need to take the first ten digits of the sum. I won't put any code here, though.