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
  
    > generate(int numRows) {
		std::vector
   
     vec; std::vector
    
     > 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; } };