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?
还是杨辉三角，注意v[i - 1] + v[i] 递推要逆序。哈
class Solution { public: vector<int> getRow(int rowIndex) { rowIndex ++; vector<int>v(rowIndex ); if (rowIndex == 1) v[0] = 1; else if (rowIndex == 2) v[0] = 1,v[1] = 1; else { v[0] = 1,v[1] = 1; for (int i = 2; i < rowIndex; ++i) { v[i] = v[i - 1]; for (int j = i; j >= 0; --j) { if (j == 0) v[i] = v[0]; else v[j] = v[j] + v[j - 1]; } } } return v; } };
原文：http://www.cnblogs.com/pk28/p/7228365.html