CPP

c++ vector resize

std::vector<int> 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}

3d vector c++ resize

dp.resize(n+1,vector<vector<int>>(n+1,vector<int>(n+1,-1)));

Resize vector c++

resize (size_type n, const value_type& val);

The resize() method (and passing argument to constructor is equivalent to that)
  
will insert or delete appropriate number of elements to the vector to make it

given size (it has optional second argument to specify their value).