6-5 先序输出叶结点 分数 10

void PreorderPrintLeaves(BinTree BT)
{
    if (!BT)
        return;

    if (!BT->Left && !BT->Right)
        printf(" %c", BT->Data);

    PreorderPrintLeaves(BT->Left);
    PreorderPrintLeaves(BT->Right);
}