119. Pascal's Triangle II

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problem

solution

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class Solution {
public:
    vector<int> getRow(int rowIndex) {
        vector<int> ret{1};
        for(int i=1;i<=rowIndex ; ++i){
            int pre = ret[0];
            for(int j=1;j<i ; ++j){
                int cur = ret[j];
                ret[j] += pre;
                pre = cur;
            }
            ret.push_back(1);
        }
        return ret;
    }
};

analysis

  • time complexity O(n)
  • space complexity O(n)