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

if(numRows==0)

return vector<vector<int>>();

vector<vector<int>>pascal(numRows);

```
for(int i = 0 ; i < numRows;++i){
pascal[i].resize(i+1);
}
for(int i = 0;i<numRows;++i){
for(int j = 0 ; j <=i;++j)
{
if(j==0||j==i) //at the edge of the triangle,it's must be 1
pascal[i][j]=1;
else{
pascal[i][j] = pascal[i-1][j-1] + pascal[i-1][j];
//1
//11
//121
//1331
//14641
}
}
}
return pascal;
}
```