MRs_369's blog

Probably, the solution is executed with error 'uninitialized value usage' on the line 38
By MRs_369, history, 5 years ago, In English

Hi guys, what did that mean " Probably, the solution is executed with error 'uninitialized value usage' on the line 38 " ?

and thank's in advance

  • Vote: I like it
  • 0
  • Vote: I do not like it

Comments Comments (3)
| Write comment?
»
5 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Let's say you've declared an integer n that denotes the number of elements to be input. In C/C++, if you don't initialise your variables (manually or through input), they're likely going to contain some junk value, say -431094 or whatever that was present there previously. Now, imagine what happens if you try to declare a vector of size n. Boom. There are various places where this might cause an issue but I'm not going to mention all of the ones I know.

In your case, which I found in your submissions, xx and yy are uninitialized to begin with. So, when you do an equality check, CF tools detect this and flag it as RTE.

→ Reply
  • »
    »
    4 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    include <bits/stdc++.h>

    using namespace std;

    int main() { int n,a[n+1]; // Probably, the solution is executed with error 'uninitialized value usage' on the line scanf("%d", &n);

    for(int i=0; i<n; i++) {
     scanf("%d", &a[i]);
}
sort(a,a+n);

long long moves = 0;

for(int i=1; i<=n; i++) {
    moves += abs(a[i]-i);
}

printf("%I64d", moves);

return 0;

    }

    Why can't I declare a[n+1]. Please reply, thanks in advance!

    → Reply
    • »
      »
      »
      4 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      1) That syntax is not part of C++, it's work only as GCC extension;
      2) What do you mean by "can't declare"? You getting some compilation error or what? With extension you can declare array that way;
      3) In your code (seriously plz use some formatting in comments — it's horrible to read) problem is you use variable $$$a[n]$$$ which you never read.

      → Reply