118Pascal's Triangle

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>> ans;for(int i = 1; i <= numRows; ++i){vector<int> cur;if(i == 1) {cur.push_back(1);ans.push_back(cur);}else {for(int j = 0;j <= i;j++){if(j == 0 || j == i) cur.push_back(1);else cur.push_back(ans[i-1][j-1] + ans[i-1][j]);}ans.push_back(cur);}}return ans;    }};