To be used in DP problems:
vector<vector<int>>dp; //global init
dp = vector<vector<int>>(n,vector<int>(m,0)); // local init for test cases
where,
n, m = dimensions of matrixauto M = 4; // num of rows
auto N = 3; // num of cols in each row
auto default_value = 1; // default value of all int elements
std::vector<std::vector<int>> matrix(M, std::vector<int>(N, default_value));vector<vector<int> > vec( n , vector<int> (m, 0));// Initializing 2D vector "vect" with
// values
vector<vector<int> > vect{ { 1, 2, 3 },
{ 4, 5, 6 },
{ 7, 8, 9 } };