标签：分析 example factor span extra log 代码 ++ etc
Given an index k, return the kth row of the Pascal‘s triangle. （Easy）
For example, given k = 3,
Return [1,3,3,1].
Note:
Could you optimize your algorithm to use only O(k) extra space?
分析：
上一题的followup，注意只能开O(k)的空间，实际上就是利用滚动数组的解法，每一行只与其上一行有关。
代码：
1 class Solution { 2 long long factorial(int n) { 3 long long result = 1; 4 for (int i = 1; i <= n; ++i) { 5 result *= i; 6 } 7 return result; 8 } 9 public: 10 vector<int> getRow(int rowIndex) { 11 vector<int> result{1}; 12 vector<int> oldVec; 13 for (int i = 2; i <= rowIndex + 1; ++i) { 14 result.push_back(1); 15 oldVec = result; 16 for (int j = 1; j < i - 1; ++j) { 17 result[j] = oldVec[j - 1] + oldVec[j]; 18 } 19 } 20 return result; 21 } 22 };
LeetCode119 Pascal's Triangle II
标签：分析 example factor span extra log 代码 ++ etc
原文地址：http://www.cnblogs.com/wangxiaobao/p/6091159.html
