二叉樹的結構定義

typedef struct BiTNode
{
    char data;
    struct BiTNode *lchild, *rchild, *parent;
}BiTNode, *BiTree;

二叉排序樹的插入

int BST_Insert(BiTree &T, int key)      //二叉排序樹的插入
{
    if(T == NULL)
    {
        T = (BiTree)malloc(sizeof(BiTNode));
        T->data = key;
        T->lchild = NULL
 
;
        T->rchild = NULL;
        return 1;           //表示插入成功
    }
    else if(key == T->data)
    {
        return 0;           //表示樹中已有該樹，插入失敗
    }
    else
    {
        if(key < T->data)   //插入到左節點
        {
            return BST_Insert(T->lchild, key);
        }
        else                //插入到右節點
 

        {
            return BST_Insert(T->rchild, key);
        }
    }
}

創造二叉排序樹

void Create_BST(BiTree &T, int str[], int n)   //創造二叉排序樹
{
    T = NULL;

    int i = 0;

    while(i<n)
    {
        BST_Insert(T, str[i]);
        i++;
    }
}

判斷一顆樹是否為BST

int pred = -32767;              //pre為無窮小
 

int JudgeBST(BiTree T)          //判斷一顆樹是否為BST
{
    int b1, b2;
    if(!T)
    {
        return 1;
    }
    else
    {
        b1 = JudgeBST(T->lchild);  //判斷左子樹是否為BST
        if(b1 == 0 || pred>T->data)
        {
            return 0;
        }
        pred = T->data;           //儲存當前節點
        b2 = JudgeBST(T->rchild);  //判斷右子樹
        return b2;
    }
}