可变大小多维数组

Question

What is problem with my code for variable size multidimensional array.How to fix this problem. My code is not passing all test cases.Can anyone help me to fix it.This is question from hackerrank challenge.

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n,q;
    cin>>n;
    cin>>q;
    int *arr[n];  
    for(int i=0;i<n;i++)
    {
       int x;
       cin>>x;
       int b[x];
       for(int j=0;j<x;j++)
       {
           cin>>b[j];
       } 
       arr[i]=b;
    }
    while(q--)
    {
        int i,e;
        cin>>i>>e;
        cout<<arr[i][e]<<endl;
    }
    return 0;
}

Answer 1

Here is correct code.

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n,q;
    cin>>n;
    cin>>q;
    int *arr[n];   // passed all test cases
    for(int i=0;i<n;i++)
    {
       int x;
       cin>>x;
       int *b=new int[x];
       for(int j=0;j<x;j++)
       {
           cin>>b[j];
       } 
       arr[i]=b;
    }
    while(q--)
    {
        int i,e;
        cin>>i>>e;
        cout<<arr[i][e]<<endl;
    }
    return 0;
}