【LeetCode】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?

Solution：

 1 class Solution {
 2 public:
 3      vector<int> getRow(int rowIndex){
 4          vector<int> v(1,1);
 5          if(rowIndex==0)return v;
 6          vector<vector<int>> vec;
 7          vec.push_back(v);
 8
 9          int n=1;
10          while(n<=rowIndex){
11              v.clear();
12              v.push_back(1);
13              for(int i=1;i<vec[n-1].size();i++){
14                  v.push_back(vec[n-1][i-1]+vec[n-1][i]);
15              }
16              v.push_back(1);
17              vec.push_back(v);
18              n++;
19          }
20          return v;
21      }
22  };

【LeetCode】119 - Pascal's Triangle II