dp.resize(n+1,vector>(n+1,vector(n+1,-1)));
std::vector vec = {1, 2, 3}; vec.resize(2); // {1, 2} vec.resize(4); // {1, 2, 0, 0,} vec.resize(6, 9); // {1, 2, 0, 0, 9, 9}