输入行数，约定 1 <= lineCount <= 9，输出以下图形。应在 C++ 代码横线处填入（ ）。
输入行数量: 9
1
1 2 1
1 2 3 2 1
1 2 3 4 3 2 1
1 2 3 4 5 4 3 2 1
1 2 3 4 5 6 5 4 3 2 1
1 2 3 4 5 6 7 6 5 4 3 2 1
1 2 3 4 5 6 7 8 7 6 5 4 3 2 1
1 2 3 4 5 6 7 8 9 8 7 6 5 4 3 2 1
int lineCount = 0;
cout << "请输入行数量:";
cin >> lineCount;
for (int i = 0; i < lineCount; i++) {
for (int j = 0; j < ____________; j++) // 此处填写代码
cout << ' ';
for (int j = 1; j < i + 1; j++)
cout << j << " ";
for (int j = i + 1; j > 0; j--)
cout << j << " ";
cout << endl;
}
- A.
(lineCount - i - 1) * 2 - B.
(lineCount - i) * 2 - C.
lineCount - i - 1 - D.
lineCount - i