/**

*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:

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

vector<vector<int> > res;

if(numRows == 0)

return res;

vector<int> pasc;

pasc.push_back(1);

res.push_back(pasc);

if(numRows == 1)

return res;

pasc.push_back(1);

res.push_back(pasc);

if(numRows == 2)

return res;

for(int i = 3; i <= numRows; i++)

{

vector<int> temp ;

temp.push_back(1);

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

temp.push_back(pasc[j-1]+pasc[j]);

temp.push_back(1);

res.push_back(temp);

pasc = temp;

}

return res;

}

};