一、题目

Given an integer rowIndex, return the rowIndexth (0-indexed) row of the Pascal’s triangle.

In Pascal’s triangle, each number is the sum of the two numbers directly above it as shown:

Example 1:

Input: rowIndex = 3
Output: [1,3,3,1]
Example 2:

Input: rowIndex = 0
Output: [1]
Example 3:

Input: rowIndex = 1
Output: [1,1]

Constraints:

0 <= rowIndex <= 33

Follow up: Could you optimize your algorithm to use only O(rowIndex) extra space?

二、题解

class Solution {
public:vector<int> getRow(int rowIndex) {vector<int> before(1,1);if(rowIndex == 0) return before;int row = 1;while(rowIndex--){vector<int> res(row + 1,1);for(int i = 1;i < row;i++) res[i] = before[i-1] + before[i];before = res;row++;}return before;}
};