I am getting stack smash error specifically on moodle - c++

Question

I have ran the same code on my local compiler and it works perfectly but for some reason on moodle it runs , gives an output and at the end gives a stack smash error. Is it because of the sscanf?
Here is the input:
10
(1,3)
(12,10)
(6,5)
(22,13)
(2,15)
(35,-10)
(15,-15)
(20,5)
(12,-8)
(1,-10)
#include<iostream>
#include<vector>
#include<cstdio>
#include<string>
#include<stdlib.h>
using namespace std;
int arr[20] , arr2[20],end = 0;
struct Point
{int x, y;
};
Point p0;
Point nextToTop(vector<Point> &S)
{
Point p = S.front();
S.erase(S.begin());
Point res = S.front();
S.insert(S.begin(),p);
return res;
}
void swap(Point &p1, Point &p2)
{Point temp = p1;
p1 = p2;
p2 = temp;
}
int distSq(Point p1, Point p2)
{return (p1.x - p2.x)*(p1.x - p2.x) +
(p1.y - p2.y)*(p1.y - p2.y);
}
int orientation(Point p, Point q, Point r)
{int val = (q.y - p.y) * (r.x - q.x) -
(q.x - p.x) * (r.y - q.y);
if (val == 0) return 0;
return (val > 0)? 1: 2;
}
int compare(const void *vp1, const void *vp2)
{
Point *p1 = (Point *)vp1;
Point *p2 = (Point *)vp2;
int o = orientation(p0, *p1, *p2);
if (o == 0)
return (distSq(p0, *p2) >= distSq(p0, *p1))? -1 : 1;
return (o == 2)? -1: 1;
}
void convexHull(Point points[], int n)
{
int ymin = points[0].y, min = 0;
for (int i = 1; i < n; i++)
{
int y = points[i].y;
if ((y < ymin) || (ymin == y &&
points[i].x < points[min].x))
ymin = points[i].y, min = i;
}
swap(points[0], points[min]);
p0 = points[0];
qsort(&points[1], n-1, sizeof(Point), compare);
int m=1;
for (int i=1; i<n; i++)
{
while (i < n-1 && orientation(p0, points[i],
points[i+1]) == 0)
i++;
points[m] = points[i];
m++;
}
if (m < 3) return;
vector<Point> S;
S.insert(S.begin(),points[0]);
S.insert(S.begin(),points[1]);
S.insert(S.begin(),points[2]);
for (int i = 3; i < m; i++)
{
while (S.size()>1 && orientation(nextToTop(S), S.front(), points[i]) != 2)
S.erase(S.begin());
S.insert(S.begin(),points[i]);
}
vector<Point> S2 = S;
int k=0;
while(S2.size()>0){
Point a = S2.front();
arr[k] = a.x;
arr2[k] = a.y;
S2.erase(S2.begin());
k++;
}
int c,d;
for(int j = 0; j<k;j++){
for(int i = j+1; i<k;i++){
if(arr[j]>arr[i]){
c = arr[j];
d = arr2[j];
arr[j] = arr[i];
arr2[j] = arr2[i];
arr[i] = c;
arr2[i] = d;
}else if(arr[j] == arr[i]){
c = arr[j];
d = arr2[j];
if(arr2[j] > arr2[j]){
arr[j] = arr[i];
arr2[j] = arr2[i];
arr[i] = c;
arr2[i] = d;}}}}
for(int j =0;j<k;j++)
{cout << "(" << arr[j] << "," << arr2[j] <<")" << endl;
}}
int main()
{int n;
cin>>n;
Point points[n] ;
int a,b;
char c[5];
for(int i=0;i<n;i++){
cin>>c;
sscanf(c, "(%d,%d)", &a,&b);
points[i] = {a,b};}
convexHull(points, n);
return 0;
}
Here is the output picture

Answer 1

I looked at your code, and I think problem is in sscanf, and solution is actually simple.
Try to change declaration of string ( char array ) in main function from char c[5]; to char c[10]; it can be any other number, but I think, if you enter even bigger numbers and c[10] will make error, so I recommend you to make it char c[50]; or because you're using integers I think char c[25]; will be fine.