Question

Link- SUPW

This is my code for SUPW in python-

n = int(input())
c = list(map(int,input().strip().split()))  
if n <= 3:
    print(min(c))
else:   
    cost = [c[0],c[1],c[2]]
    for i in range(3,n):
        cost.append(c[i] + min(cost[i-3:i]))
    print(min(cost[n-3:]))

This is giving accepted for all test cases except for test case 2 in which it is giving Runtime Error. Can someone tell me the reason or provide a test case where it fails.

So what I have done is that-

Cost[i] = min time if we work that day.

So cost[0] = c[0],
   cost[1] = c[1],
   cost[2] = c[2]
And for the rest it is c[i] + min of the previous 3 elements.
And the answer is the min of the last 3 elements.

Accepted Answer

Dont have any debugging experience in python , but I got AC with the same logic but I used C++ , here is my code,

#include <iostream>
#include <vector>
#include <algorithm>

int main(){
    int n;
    std::cin >> n;
    std::vector<int>dutyTime(n);
    for(int i=0;i<n;i++){
        std::cin >> dutyTime[i];
    }
    std::vector<int>bestTime(n);
    bestTime[0] = dutyTime[0];
    bestTime[1] = dutyTime[1];
    bestTime[2] = dutyTime[2];
    for(int i=3;i<n;i++){
        bestTime[i] = dutyTime[i]+std::min(bestTime[i-1],std::min(bestTime[i-2],bestTime[i-3]));
    }

    std::cout << std::min(bestTime[n-1],std::min(bestTime[n-2],bestTime[n-3])) << std::endl;

    return 0;
}

Probably I would use c = raw_input(); timeList = c.split(" "); ##then a for loop for converting it to int list rather than list(map(int,input().strip().split())) but thats all upto you , i prefer the previous one for its readability and easy to debug'ness'.

Answer 2

1

OK, so I finally found the bug. I submitted a solution which was the following-

Take the input. That's it.

It was still showing error on test-case 2.

Then I submitted a solution in which it said that if there's a character which is non numeric and it is not a space then it raises an error and it did on test case 2.

So finally I submitted a solution in which it took input in such a way that it did not include alphabetical characters and I got AC.

Thanks by the way mz54. I don't have enough karma to upvote else I would have upvoted your help. Here is my solution-

n = int(input().strip())
c = input().strip().split()
j = 0
while j < n:
    try:
        c[j] = int(c[j])
    except:
        pass
    finally:
        j += 1
n = len(c)
if n <= 3:
    print(min(c))
else:   
    for i in range(3,n):
        c[i] += min(c[i-3:i])
    print(min(c[n-3:]))

My solution

link

answered 14 Nov '16, 19:47

5★mathecodician
2.6k●6●29
accept rate: 7%

It took about 30-35 submissions.

(14 Nov '16, 20:11) mathecodician5★

2

The same thing happened in the problem Wormholes in which the problem was that it said that the next n lines will give the time of the contest but in 2 test cases there were not n lines but less then that so I was taking extra input and again I had to add a try-except block.

(16 Nov '16, 15:02) mathecodician5★

Thanks a lot @mathecodician. I had been trying to solve that SUPW problem for months and everytime it gave me error on the second test. Your suggestion to take input in such a way so that it does not include characters other than numbers helped a lot. It finally worked after 30-40 tries!! Thanks a lot! :)

(19 May '17, 20:07) akashbhalotia2★

@mathecodician

I am facing same issue in warmholes problem, can you please answer the question on the link below.

https://discuss.codechef.com/questions/122165/not-getting-ac-in-warmhole-problem

(04 Feb, 17:16) arpit7282★

Answer 3

For Java users, just do the conversion from String to integer inside the try block and also make a catch block to catch the exception. Like this:-

  N=Integer.parseInt(br.readLine()); //array length

  String s[]=br.readLine().trim().split(" "); //accepting the time for each SUPW work
  int a[]=new int[N];


  for(i=0;i<N;i++) //converting from String to integer
  {
    int ch=0;
    try
    {
        ch=Integer.parseInt(s[i].trim());
    }
    catch(Exception e)
    {
    }
    a[i]=ch;
  }

This will work :)

[closed] ZCO 14 SUPW

The question has been closed for the following reason "The question is answered, right answer was accepted" by mathecodician 18 Mar '17, 19:55

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