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 > generate(int numRows) { vector > ve; vector ve1; if(numRows==0) return ve; ve1.push_back(1); ve.push_back(ve1); if(numRows==1) return ve; ve1.clear(); ve1.push_back(1); ve1.push_back(1); ve.push_back(ve1); if(numRows==2) return ve; int i; int j; for(i=2;i