Leetcode 109

//这种也是空间复杂度为O(K)的解法，就是边界有点难写
class Solution {
public:
    vector<int> getRow(int rowIndex) {
        vector<int> res;
        res.push_back(1);
        if(rowIndex == 0) return res;
        res.push_back(1);
        if(rowIndex == 1) return res;
        for(int i=2;i <= rowIndex;i++){
            res.push_back(0);
            int a = res[0];
            int b = res[1];
            for(int j=1;j < i;j++){
                res[j] = a+b;
                a = b;
                b = res[j+1];
            }
            res[i] = 1;
        }
        return res;
    }
};