[C++]VECTOR ALLOCATION

Basis

Define：vector<int> array;

Two dynamic vector +initialize  0：

vector<vector<int> > array;
array.resize(y, vector<int>(x, 0));

OR

vector<vector<int> > array(y, vector<int>(x, 0));
**
vector<vector<int> > array(y, vector<int>(x));//ALSO '0'