LeetCode Pascal's Triangle2

Description

Given an index k, return the kth row of the Pascal’s triangle.

For example, given k = 3,
Return [1,3,3,1].

The original problem is here.

The original code is here.

My Solution

I solve this problem in C++, as below:

/*Pascal's Triangle II 
*Author: shuaijiang
*Email: zhaoshuaijiang8@gmail.com
*/
#include<iostream>
#include<stdlib.h>
using namespace std;

class Solution {
public:
    vector<int> getRow(int rowIndex) {
        vector<int> lastRow;
        vector<int> row;
        if(rowIndex < 0)
            return row;

        lastRow.push_back(1);

        if(rowIndex == 0)
            return lastRow;
            
        for(int i=1;i<=rowIndex;i++){
            int num = 0;
            row.push_back(1);
            for(int j=1;j<i;j++){
                num = lastRow[j-1] + lastRow[j];
                row.push_back(num);
            }
            row.push_back(1);
            lastRow = row;
            row.clear();
        }
        return lastRow;
    }
};

Note

The number at index i of each row(except the begin and the end) is the sum of the numbers at index i-1 and i of the last row.