Day-12 Pascal's Triangle II

class Solution {
  private int getNum(int row, int col) {
    if (row == 0 || col == 0 || row == col) {
      return 1;
    }

    return getNum(row - 1, col - 1) + getNum(row - 1, col);
  }

  public List<Integer> getRow(int rowIndex) {
    List<Integer> ans = new ArrayList<>();

    for (int i = 0; i <= rowIndex; i++) {
      ans.add(getNum(rowIndex, i));
    }

    return ans;
  }
}

class Solution {
    public List<Integer> getRow(int rowIndex) {
        List<Integer> prev=new ArrayList<>();
        prev.add(1);
        List<Integer> res=new ArrayList<>(prev);
        for(int i=1;i<=rowIndex;i++){
            res.clear();
            res.add(1);
            for(int p=0;p<prev.size()-1;p++){
                 res.add(prev.get(p)+prev.get(p+1));
            }
            res.add(1);
            prev=new ArrayList(res);
        }
        
        return res;
    }
}

class Solution {
  public List<Integer> getRow(int rowIndex) {
    List<Integer> row =
        new ArrayList<>(rowIndex + 1) {
          {
            add(1);
          }
        };

    for (int i = 0; i < rowIndex; i++) {
      for (int j = i; j > 0; j--) {
        row.set(j, row.get(j) + row.get(j - 1));
      }
      row.add(1);
    }

    return row;
  }
}

class Solution {
  public List<Integer> getRow(int n) {
    List<Integer> row =
        new ArrayList<>() {
          {
            add(1);
          }
        };

    for (int k = 1; k <= n; k++) {
      row.add((int) ((row.get(row.size() - 1) * (long) (n - k + 1)) / k));
    }

    return row;
  }
}