variable sized arrays hackerrank solution in c++
#include <iostream>
#include <vector>
using namespace std;
int main() {
// get length of array 'a' and number of queries
int n, q;
cin >> n >> q;
// create vector of vectors
vector<vector<int>> a(n);
// fill each 2D vector i with k_i values
for (int i = 0; i < n; i++) {
// get the length k of the vector at a[i]
int k;
cin >> k;
// fill the vector with k values
a[i].resize(k);
for (int j = 0; j < k; j++) {
cin >> a[i][j];
}
}
// run queries on a
for (int q_num = 0; q_num < q; q_num++) {
// get i, j as the 'query' to get a value from a
int i, j;
cin >> i >> j;
cout << a[i][j] << endl;
}
return 0;
}