Getting different output for same code on Google server and on my machine

1

I tried today’s Google Kick Start round F problem 1(ATM Queue). I wrote a code which I will attach below. When I ran it on my laptop to verify if sample cases were running fine, I got the right answer. Then I submitted the solution on Google Kick Start site and I got Sample Failed:WA . When I ran the given sample input on their site, I got a different output than what I got on my local machine. Can anyone tell me what might be the reason for this.

The outputs on my machine and google server are as follows:

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and my code is:

for case in range(1, int(input())+1):
    n,x=map(int,input().split())
    people=list(map(int, input().split()))
    order=[]
    if not any(i>x for i in people):
        print(people)
        continue
    people={people.index(i)+1:i for i in people}
    while len(list(people.keys()))>0:
        k=list(people.keys())[0]
        j=people[k]
        if j<=x:
            order.append(k)
            people.pop(k)
        else:
            people[k]=(people.pop(k))-x
    print("Case #{}: {}".format(case," ".join(list(map(str, order)))))
2

I do not use python, but one common mistake for getting different output on two different servers, on the same input is declaring an array/integer without any value in it

Eg.

int n; //declaring n as an integer
cin >> n; //inputting n
int a[n + 1]; //declaring an array of length n+1
cout << a[0] << endl; //outputting a[0]

The above code can give 0 as a result, and some other garbage value on another server too.

The key here is to initialize all the array values with 0 or any other suitable integer.

So

for(int i = 0; i <= n; i++) { //for loop from 0 to n
    a[i] = 0; //initializing a[0], a[1], a[2]....a[n] to 0
} //end of for loop

This code does the work.

If this wasn’t your problem, ignore this reply please xD.

3

I think the order of items of dictionaries may depend on Python implementation. By sure dict is not the data structure you need to the task

2 Likes
4

Hi @aryan12
I appreciate your help but there is no concept of garbage value in Python. With Python, we need not worry about the garbage value thing like in C++.

But thanks for your time🙂

5

Ya maybe this can be done without dictionary but I am a beginner in CP and I can’t really find another way of doing it.

But if dict is the problem then I should get WA on my machine also. On my machine it is correct.

6

nop, that’s what I’m I telling, the order the items present in the dictionary may be not the same in your machine than in judge system. It’s just a casuality that for this particular testcase your dict arrange the items in such a way that the answer is correct but I will not work on other testcases or other systems configurations

7

Ok thanks for letting me know.

Can you please suggest another method of doing this question?

8

the number of times that person i needs to stand at the end of the queue can be calculated as (a_i-1)/x, so you can do this:

  • build an array of pairs { [(a_1-1)/x; 1], [(a_2-1)/x; 2], ... , [(a_n-1)/x; n]}
  • sort the array
c++ code 
int n,x;
cin>>n>>x;
vector<pair<int,int>> a(n);
for(int i=0;i<n;++i) {
    int y;cin>>y;
    a[i].first=(y-1)/x,a[i].second=i+1;
}
sort(a.begin(),a.end());
for (int i=0;i<n;++i) cout << a[i].second << " ";
9

Ok thanks for the help