vector of vectors c++

vector> is a data structure in C++ that is used to store a dynamic 2D array. To declare a vector of vectors, you can use the following syntax:

#include <vector>
using namespace std;

vector<vector<int>> matrix;

To initialize the vector of vectors with a specific size and value, you can use the following example:

int rows = 3;
int cols = 4;
int initialValue = 0;
vector<vector<int>> matrix(rows, vector<int>(cols, initialValue));

To access and modify elements in the vector of vectors, you can use the following syntax:

int value = matrix[1][2]; // Accessing the element at row 1, column 2
matrix[0][3] = 10; // Modifying the element at row 0, column 3

To iterate through the vector of vectors, you can use nested loops:

for (int i = 0; i < matrix.size(); i++) {
    for (int j = 0; j < matrix[i].size(); j++) {
        // Access and process matrix[i][j]
    }
}