119. 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?

用滚动数组

class Solution {public:vector<int> getRow(int rowIndex) {vector<int> row(rowIndex + 1);for (int i = 0; i <= rowIndex; i++){for (int j = i; j >= 0; j--){if (j == i || j == 0){row[j] = 1;}else{row[j] = row[j] + row[j - 1];}}}return row;}};