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> res; if(rowIndex<0)return res; res.resize(rowIndex+1); res[0]=1; for(int i=1;i<=rowIndex;i++) { for(int j=i;j>=0;j--) { if(j==0||j==i)res[j]=1; else res[j]=res[j]+res[j-1]; } } return res; } };