Pascal's Triangle II

Given an index k, return the kth row of the Pascal's triangle.
For example, given k = 3,

Return

[1,3,3,1]

.
Note:

Could you optimize your algorithm to use only O(k) extra space?

class Solution {
public:
vector<int> getRow(int rowIndex) {
vector<int> result(rowIndex+1);
result[0] = 1;
for(int i=1;i<=rowIndex;i++){
for(int j=i;j>0;j--){
if(j == i){
result[j] = result[j-1];
}else{
result[j] = result[j] + result[j-1];
}
}
}
return result;
}
};