Pascal's triangle II@leetcode

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Given an index k, return the k^th 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?

» Solve this problem

	class Solution {
	public:
	vector<int> getRow(int rowIndex) {
	// Start typing your C/C++ solution below
	// DO NOT write int main() function
	vector<int> res1, res2;
	res1.push_back(1);
	for(int i=1; i<=rowIndex; i++)
	{
	if(i%2==1)
	{
	for(int j=0; j<=i; j++)
	{
	if(j==0||j==i)
	res2.push_back(res1[0]);
	else
	res2.push_back(res1[j-1]+res1[j]);
	}
	res1.clear();
	}
	else
	{
	for(int j=0; j<=i; j++)
	{
	if(j==0||j==i)
	res1.push_back(res2[0]);
	else
	res1.push_back(res2[j-1]+res2[j]);
	}
	res2.clear();
	}
	}
	return res1.empty()? res2:res1;
	}
	};

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