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Pascal's Triangle II <leetcode>

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?

 

算法:根据帕斯卡三角形的规律直接求,比较简单,可能有其他好的方法,代码如下:

 

 1 class Solution { 2 public: 3     vector<int> getRow(int rowIndex) { 4         vector<int>  temp(rowIndex+1); 5         vector<int>  pre(rowIndex+1); 6         pre[0]=1; 7         for(int i=0;i<=rowIndex;i++) 8         { 9             temp[0]=1;10             temp[i]=1;11             for(int j=1;j<i;j++)12             {13                 temp[j]=pre[j-1]+pre[j];14             }15             pre=temp;16         }17         return temp;18     }19 };

 

Pascal's Triangle II <leetcode>