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?

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Array

vector<int> getRow(int rowIndex) {
vector<int> result(1,1);
if(rowIndex==0)return result;
result.push_back(1);
if(rowIndex==1)return result;
int i=2;
while(i!=rowIndex+1)
{
vector<int> tmp(result);
for(int j=1;j<i;j++)
{
result[j]=tmp[j-1]+tmp[j];
}
result.push_back(1);
i++;
}
return result;
}