LeetCode-Pascal's Triangle II

class Solution {
public:
    vector<int> getRow(int rowIndex) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        vector<int> ans(rowIndex + 1, 0);
        ans[0] = 1;
        for (int i = 0; i < rowIndex; ++i)
        {
            int pre = 1;
            int cur;
            for (int j = 1; j <= i + 1; ++j)
            {
                cur = ans[j];
                ans[j] += pre;
                pre = cur;
            }
        }
        return ans;
    }
};