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].

这就是杨辉三角

class Solution {public:    vector<int> getRow(int rowIndex) {        vector<int> row(rowIndex + 1, 1);        for (int i = 1; i <= rowIndex; i++) {            int prev = 1;            for (int j = 1; j < i; j++) {                int temp = row[j];                row[j] += prev;                prev = temp;            }        }        return row;    }};