How can I modify a 2D vector in C++?

How can I modify a 2D vector in C++?

You can modify a 2D vector in C++ by accessing its elements using indices. For example, if you have a vector named vec, you can change an element like this: vec[i][j] = newValue;.

What if I want to add a new row to the 2D vector?

To add a new row, you can use the push_back method. For example: vec.push_back(std::vector<int>(newRowSize)); will add a new row with the specified size.

How do I access the size of the 2D vector?

You can access the number of rows with vec.size() and the number of columns in the first row with vec[0].size(), assuming the vector is not empty.

Can I resize an existing row?

Yes, you can resize an existing row using the resize method. For example: vec[i].resize(newSize); will change the size of the row at index i.