Pascal'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]]

Discuss

class Solution {public:    vector<vector<int> > generate(int numRows) {        vector<vector<int>> ve;        vector<int>         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<numRows;i++)        {            ve1.clear();            ve1.push_back(1);            for(j=0;j<i-1;j++)            ve1.push_back(ve[i-1][j]+ve[i-1][j+1]);            ve1.push_back(1);            ve.push_back(ve1);        }        return ve;    }};