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  1. Prepare
  2. C++
  3. Introduction
  4. Variable Sized Arrays
  5. Discussions

Variable Sized Arrays

  • fahad_khan44604
     + 1 comment

    The following include two solutions

    1. Using Vectors
    int main() {
    int rows, q;
    cin >> rows >> q;
    
    vector<vector<int>> matrix(rows);
    for(int i=0; i<rows; i++) {
       int cols;
       cin >> cols;
       matrix[i].resize(cols);
       
       for(int j=0; j<cols; j++) cin >> matrix[i][j];
    }
    
    // for query part
    for(int i=0; i<q; i++) {
        int row, col;
        cin >> row >> col;
        cout << matrix[row][col] << endl;
    }
    return 0;
}
    1. Using normal Arrays
    int main() {
    int rows, q;
    cin >> rows >> q;
    
    int ** matrix = new int*[rows];
    
    // taking inputs
    for(int i=0; i<rows; i++) {
       int cols;
       cin >> cols;
       matrix[i] = new int[cols];
       
       for(int j=0; j<cols; j++) cin >> matrix[i][j];
    }
    
    // for query part
    for(int i=0; i<q; i++) {
        int row, col;
        cin >> row >> col;
        cout << matrix[row][col] << endl;
    }
    
    // delete dynamically allocated memory
    for(int i=0; i<rows; i++) {
        delete[] matrix[i];
    }
    delete[] matrix;
    return 0;
}

    The logic is same TC -> O(n * m) where n is rows and m is columns