Variable Sized Arrays | HackerRank

Goal

Create N number of variable-length arrays and find a element from quaries

Solution

If you know vector in C++, it would be easy problem.

you initialize vector of vector a and insert variable sized vector into a.

# Variable Sized Arrays

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    int n = 0;
    int q = 0;
    
    cin >> n >> q;
    
     vector<vector<int>> a;
    
    for(int i = 0 ; i < n ; i++){
        int k = 0;
        
        cin >> k;
        
        vector<int> v;
        
        int value = 0;
        int index = 1;
        while(cin >> value){
            
            v.push_back(value);
            index++;
            
            if (index > k){
                break;
            }
            
        }
        
        a.push_back(v);
        
    }
    
    for(int i = 0; i < q ; i++){
        int index, j ;
        cin >> index >> j;
        cout << a[index][j] << endl;
    }
    
    
    return 0;
}