-1

I get the following error on running the code below: I am trying to solve a LeetCode problem and I get this error. I changed the datatype from int to long long int but I still get it. Can someone please help me ?

Line 130: Char 39: runtime error: signed integer overflow: 2147453785 + 36049 cannot be represented in type 'int' (stl_numeric.h)
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/stl_numeric.h:139:39

The code I have written is:

class Solution {
public:
    int minimumAverageDifference(vector<int>& nums) {
        long long int n = nums.size();
        long long int sumfromstart = 0;
        long long int sumfromend = accumulate(nums.begin(),nums.end(),0);
        int res = INT_MAX;
        int index = 0;
        for(int i=0; i<n; i++)
        {
            sumfromstart += nums[i];
            sumfromend -= nums[i];
            int a = sumfromstart/(i+1);
            int b = (i == n-1) ? 0 : sumfromend/(n-i-1);
            int avg = abs(a-b);
            if(avg < res)
            {
                res = avg;
                index = i;
            }
        }
        return index;
    }
};
Ojaswi Awasthi
  • 27
  • 7
  • 5
    This is a bit of a trap. In the call to `std::accumulate`, the last argument doesn't just give the starting value; it gives the type of the accumulator. So change that `0` to `0LL`. – Pete Becker Dec 04 '22 at 20:46
  • 4
    Please don't use scam coding websites to learn C++. They won't teach you anything good. Here is a much better source of knowledge: [The Definitive C++ Book Guide and List](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list). – Evg Dec 04 '22 at 20:47
  • When you asked this question on the LeetCode forums, what answers did you get? – Eljay Dec 04 '22 at 23:11

1 Answers1

4

std::accumulate is a templated function that in this case is defined as follows (prior to C++20):

template< class InputIt, class T >
T accumulate( InputIt first, InputIt last, T init );

Since accumulate returns a value of type T, and the type of the third parameter (T init) is of type T, whatever type you pass as the third parameter will be used to accumulate the result value. In your case, that's type int, because:

        //                                This is a literal of type `int`
        //                                                            ▼
        long long int sumfromend = accumulate(nums.begin(),nums.end(),0);
        //                       ▲
        //  Implicit cast from `int` to `long long int`

You can fix this by using a literal of type long long (that's the short-form for long long int) instead, which is defined by appending 2 l or L characters to the end of a number literal, like this:

        //                            This is a literal of type `long long`
        //                                                            ▼▼▼
        long long int sumfromend = accumulate(nums.begin(),nums.end(),0LL);
        //                       ▲
        //              No typecast required
radj307
  • 439
  • 4
  • 11