What is wrong with my code

#1 
#include<iostream>
#include<algorithm>
#include<climits>
using namespace std;
bool isvalid(int a[],int c,int n,int mid)
{  int total_pratha=0;
  
   for (int i = 0; i < c; i++)
   {     int time=0;
         int j=1;
       while (time<=mid )
       {
           time+=a[i]*j;
           j++;
       }
       total_pratha+=(j-1); 
   }
   return total_pratha>=n;
}

int main(){
    int n;
    cin>>n;
    int c;
    cin>>c;
    int a[n];
    for (int i = 0; i < c; i++)
    {
        cin>>a[i];
    }
    sort(a,a+c);
    int start=0;
    int end=0;
    for (int i = 1; i <=n; i++)
    {
        end=end+(a[0]*i);
        
    }
    int ans=INT_MAX;
    while (start<=end)
    {
        int mid=(start+end)/2;
        if (isvalid(a,c,n,mid))
        {
            ans=min(ans,mid);
            end=mid-1;
        }
        else
        {
            start=mid+1;
        }
    }
    
cout<<ans;
    return 0;
}
#2

Have debugged your code here, and have also added comments for better understanding.


If this solves your doubt, please mark it as resolved.

#3

hey please enlighten this more
(j * (j + 1)a[i]) <= 2mid

#4

This is to handle this case that, A cook with a rank R can cook 1 prata in the first R minutes 1 more prata in the next 2R minutes, 1 more prata in 3R minutes and so on(he can only cook a complete prata)