[LeetCode] 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) {
// IMPORTANT: Please reset any member data you declared, as
// the same Solution instance will be reused for each test case.
vector<int> ans;
ans.push_back(1);
for(int i = 1;i <= rowIndex;i++)
{
for(int j = i; j > 0;j--)
{
if(j == i) ans.push_back(1);
else
ans[j] = ans[j - 1] + ans[j];
}
}
return ans;
}
};