```
class Solution {
public:
vector<int> getRow(int rowIndex) {
vector<int> result;
for(int i=0;i<=rowIndex;++i){
int last=0;
for(int j=0;j<i;++j){
int temp_int=result[j]+last;
last=result[j];
result[j]=temp_int;
}
result.push_back(1);
}
return result;
}
};
```

The idea comes from the math of combintion:P(n,k)=P(n-1,k)+P(n-1,k-1)

so we create the Triangle from top to bottom,so every row is one longer the the previous.