https://oj.leetcode.com/problems/pascals-triangle/

Q118.cpp

//C++11
class Solution {
  public:
    vector<vector<int> > generate(int numRows) {
      if (numRows <= 0) return vector<vector<int> >();
      vector<vector<int> > result;
      result.push_back(vector<int>{1});
      if (numRows == 1) return result;
      result.push_back(vector<int>{1, 1});
      if (numRows == 2) return result;
      for (int counter = 2; counter < numRows; counter++) {
        auto const& prev = result[counter - 1];
        vector<int> newRow{1};
        auto start = prev.begin() + 1, end = prev.end();
        while (start != end) {
          newRow.push_back(*start + *(start-1));
          start++;
        }
        newRow.push_back(1);
        result.push_back(newRow);
      }
      return result;
    }
};