LeetCode - Pascal's Triangle

[
[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> > result;
if(numRows<=0){
return result;
}
result.assign(numRows,vector<int>());
result[0].push_back(1);
for(int i=1;i<numRows;i++){
result[i].push_back(result[i-1][0]);
for(int j=1;j<i;j++){
result[i].push_back(result[i-1][j-1]+result[i-1][j]);
}
result[i].push_back(result[i-1][i-1]);
}
return result;
}
};