LeetCode-119-Pascal's Triangle II-E

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?

代码：

vector<int> getRow(int rowIndex) {
vector<int> res(rowIndex+1);
res[0]=1;
for(int i=1;i<=rowIndex;i++){
for(int j=i;j>0;j--){
res[j]=res[j-1]+res[j];
}
}
return res;
}