PTA数据结构与算法题目集（中文）6-11 先序输出叶结点 (15分)

// #include <stdio.h>
// #include <stdlib.h>

// typedef char ElementType;
// typedef struct TNode *Position;
// typedef Position BinTree;
// struct TNode{
//     ElementType Data;
//     BinTree Left;
//     BinTree Right;
// };

// BinTree CreatBinTree(); /* 实现细节忽略 */
// void PreorderPrintLeaves( BinTree BT );

// int main()
// {
//     BinTree BT = CreatBinTree();
//     printf("Leaf nodes are:");
//     PreorderPrintLeaves(BT);
//     printf("\n");

//     return 0;
// }

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

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

    }
}