Pascal's Triangle II

class Solution {
public:
    vector<int> getRow(int rowIndex) {
        if (rowIndex < 0) {
            throw new invalid_argument("Index must not be negative");
        }
        
        // 1
        
        vector<int> ret(rowIndex + 1, 1);
        for (int i = 3; i <= rowIndex + 1; ++i) {
            for (int j = i - 2; j > 0; --j) {
                ret[j] += ret[j - 1];
            }
        }
        return move(ret);
        
        
        // 2
        /*
        vector<vector<int>> ret(2, vector<int>());
        int pre = 0, cur = 1;
        for (int i = 0; i <= rowIndex; ++i) {
            ret[cur].assign(i + 1, 1);
            for (int j = 1; j < i; ++j) {
                ret[cur][j] = ret[pre][j] + ret[pre][j - 1];
            }
            swap(pre, cur);
        }
        
        
        return move(ret[pre]);
        */
    }
};