Given numRows, generate the first numRows of Pascal's triangle.

For example, given numRows = 5,

Return

[

     [1],

    [1,1],

   [1,2,1],

  [1,3,3,1],

 [1,4,6,4,1]

]

class Solution {

public:

    std::vector<std::vector<int> > generate(int numRows) {

		std::vector<int> vec;

		std::vector<std::vector<int>> res(numRows,vec);

		int triangle[100][100];

		for (int i = 0; i < numRows; i++)

		{

			triangle[i][0] = 1;

			triangle[i][i] = 1;

		}

		for (int i = 2; i < numRows; i++)

		{

			for (int j = 1; j < i + 1; j++)

			{

				triangle[i][j] = triangle[i-1][j-1] + triangle[i-1][j];

			}

		}

		for (int i = 0; i < numRows; i++)

		{

			for (int j = 0; j <= i; j++)

			{

				res[i].push_back(triangle[i][j]);

			}

		}

		return res;

    }

};