Runtime error on hackerrank problems for no reason? - c

Question

This is the question:
https://www.hackerrank.com/challenges/lisa-workbook/problem.
My code passes all the test cases except one. The message I get is just Run Time Error. Even if I return 0 at the beginning of the function that I am supposed to implement, I still get this error, while in all other test cases I get Wrong Answer.
This is not the only question on hacker rank where this happened. In the last couple of days I encountered 3 or 4 more questions with that one odd case that was always giving a runtime error. In the end, I had to implement a Python 3 solution (with the same logic), which passed all the test cases, to solve these problems.
I wonder if this is a bug on the website or if I am understanding something wrongly. Here is my function implementation for this problem:
int workbook(int n, int k, int arr_count, int* arr)
{
int tmp = 1, specprob = 0;
int *chstart = malloc(n * sizeof(int));
int *chend = malloc(n * sizeof(int));
for (int i = 0; i < n; i++) {
chstart[i] = tmp;
tmp += arr[i] / k - 1;
if (arr[i] % k != 0) {
tmp++;
}
chend[i] = tmp;
tmp++;
if (!(arr[i] < chstart[i])) {
int qno = 0, chpage = 1, iqno = 0;
for (int j = chstart[i]; j < chend[i] + 1; j++) {
if (chpage * k <= arr[i]) {
qno += k;
} else {
qno += (k - (chpage * k - arr[i]));
}
if (j > iqno && j < qno + 1) {
specprob++;
}
iqno = qno;
chpage++;
}
}
}
return specprob;
}

Answer 1

It looks like a bug, since when you run the empty function with just a return 0; it gives the same runtime error.
For the moment though, if you don't mind too much about the different language, you could make a few minor changes to the code to make it compile for C++ (don't forget to change the language selection too):
int workbook(int n, int k, vector<int> arr)
{
int tmp = 1, specprob = 0;
int *chstart = (int*)malloc(n * sizeof(int));
int *chend = (int*)malloc(n * sizeof(int));
for (int i = 0; i < n; i++)
{
chstart[i] = tmp;
tmp += arr[i] / k - 1;
if (arr[i] % k != 0)
{
tmp++;
}
chend[i] = tmp;
tmp++;
if (!(arr[i] < chstart[i]))
{
int qno = 0, chpage = 1, iqno = 0;
for (int j = chstart[i]; j < chend[i] + 1; j++)
{
if (chpage * k <= arr[i])
{
qno += k;
}
else
{
qno += (k - (chpage * k - arr[i]));
}
if (j > iqno && j < qno + 1)
{
specprob++;
}
iqno = qno;
chpage++;
}
}
}
return specprob;
}