STUPID MACHINE

CodeChef-DSA-learners
1 
using namespace std;

typedef long long int ll;
typedef unsigned long long ull;
typedef double db;
typedef vector<int> VI;
typedef vector<ll> VL;
typedef pair<int,int> PI;
typedef pair<ll,ll> PL;

#define w(n) while(n--)
#define f(i,n) for(ll i=1;i<=n;i++)
#define fr(i,n) for(int i=0;i<n;i++)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
int main()
{
	 ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    ll t;
    cin>>t;
    w(t)
    {
        ll n;
        cin>>n;
        ll ans=0;
        ll a[n];
        std::stack<int>st ;
        ll mn=INT_MAX;
        int index;
        fr(i,n)
        {
            ll x;
            cin>>x;
            a[i]=x;
            st.push(x);
            mn=min(mn,x);
            if(mn==x)
            {
                index=i;
            }
        }
        ans=mn*n;
        while(st.top()!=mn)
        {st.pop();}
        st.pop();
        int cnt=0;
        int k=index;
        while(!st.empty())
        {
            cnt++;
             k=index;
            mn=*min_element(a,a+k);
            while(st.top()!=mn)
            {
                st.pop();
                index--;
            }
            ans=ans+(mn-cnt)*k;
            st.pop();
        }
        cout<<ans<<"\n";
    }
    
}
why this is showing a runtime error
2

Please Format your code and link the question first.
For reference, here’s my code

My Code 
#include <iostream>
#include <bits/stdc++.h>
using namespace std;
void solve(){
    int n;
    cin>>n;
    long long int ans=0;
    for(int i=0, value=1e9;i<n;i++){
        int box;
        cin>>box;
        value=min(value, box);
        ans+=value;
    }
    cout<<ans<<'\n';
}
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
	int t;
	cin >>t;
	while(t--){
     solve();
	}
}
3

but why is that runtime error coming in my code

4

Okay a few fixes were needed.

#include<bits/stdc++.h>
using namespace std;

typedef long long int ll;
typedef unsigned long long ull;
typedef double db;
typedef vector<int> VI;
typedef vector<ll> VL;
typedef pair<int,int> PI;
typedef pair<ll,ll> PL;

#define w(n) while(n--)
#define f(i,n) for(ll i=1;i<=n;i++)
#define fr(i,n) for(int i=0;i<n;i++)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
int main()
{
	 ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    ll t;
    cin>>t;
    w(t)
    {
        ll n;
        cin>>n;
        ll ans=0;
        ll a[n];
        std::stack<int>st ;
        ll mn=INT_MAX;
        int index;
        fr(i,n)
        {
            ll x;
            cin>>x;
            a[i]=x;
            st.push(x);
            mn=min(mn,x);
            if(mn==x)
            {
                index=i;
            }
        }
        //(ll) to prevent overflow
        ans=(ll)mn*(n-index);//Only the ones you will pop
        while(st.top()!=mn)
        {st.pop();}
        st.pop();
        int cnt=0;
        int k=index;
        while(!st.empty())
        {
            cnt++;
            k=index;
            mn=*min_element(a,a+k);
            while(st.top()!=mn)
            {
                st.pop();
                index--;
            }
            st.pop();
            index--;//You need to reduce index for this pop as well. this caused The RE
            ans=ans+(ll)mn*(k-index);//Again only the ones you've popped
        }
        cout<<ans<<"\n";
    }
    
}