What is a vector of vector of point? [closed]

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A vector is a templated class that can store anything that you ask it to store when you defined it. For example: 

vector<int>      // vector that will store any number of integers
vector<double>   // vector of double precision floating points
vector<string>   // vector of strings
vector<T>        // vector of Ts, being understood that T is a type

In your case you have a vector < vector... > which means that you have a vector of vectors. In practice it’s a 2D data structure that is sometimes used to implement a matrix. 

vector<vector<int>>    // vector of vectors, aka 2D vector of integers
vector<vector<Point>>  // 2D vector of Points, where Points is a type, probably a class

Example: 

vector<vector<int>> m { { 1,  2,  3,  4}, 
                        { 5,  6,  7,  8},
                        { 9, 10, 11, 12} };
cout << m[1][2]<<endl;  // line 1, item 2 (numbering start with 0) -> 7

Now, you have to look in your source code where Point is defined. If the code compiles, it must be defined somewhere. Very probably it’s something like: 

struct Point { int x, y; };

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