CODEWITHSUNDEEP
c++arraysstlc++14c++17
Wang Wei
Wang Wei

Reputation: 3

Why does this code gives out of bounds error?

I have been trying to understand the out of bound error for the following code but I'm unable to figure out. The original problem is https://codeforces.com/contest/148/problem/A . I don't know why I am stuck and can you tell me how I can avoid similar type of errors. 

  #include <iostream>
  using namespace std;
  int main()
  {
    std::ios::sync_with_stdio(false);
    int k,l,m,n,d,count=0;

    cin>>k>>l>>m>>n>>d;
    int arr[d]={0}; 

    for (int i = 0; i < d; ++i){
      int k1=k*(i+1); k1--;
      int l1=l*(i+1); l1--;
      int m1=m*(i+1); m1--;
      int n1=n*(i+1); n1--;

      if(arr[k1]==0 && k1<d){
        arr[k1]=1; count++;
      }
      if(arr[l1]==0 && l1<d){
        arr[l1]=1; count++;
      }
      if(arr[m1]==0 && m1<d){
        arr[m1]=1; count++;
      }
      if(arr[n1]==0 && n1<d){
        arr[n1]=1; count++;
      }

    }

    cout<<count;


    return 0;
  }

Upvotes: 0

Views: 62

Answers (1)

Jeffrey
Jeffrey

Reputation: 11410

You need to check the bounds first, in:

if(arr[k1]==0 && k1<d)

with:

if(k1<d && arr[k1]==0)

The second condition will not be tested if the first one is false. But the counterpart is not true. The first condition will always be tested.

Upvotes: 1

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