基于二叉树的算法

1.统计二叉树中度为1的节点个数

int NodeCount(BiTree bt){
    if(bt == null) return 0;
    if(bt->lchild == null && bt->rchild != null || bt->lchild != null && bt->rchild == null)
        return 1+NodeCount(bt->lchild) + NodeCount(bt->rchild);
    return NodeCount(bt->lchild) + NodeCount(bt->rchild);
}

2.统计二叉树中度为2的节点个数

int NodeCount(BiTree bt){
    if(bt == null) return 0;
    if(bt->lchild != null && bt->rchild != null)
        return 1+NodeCount(bt->lchild) + NodeCount(bt->rchild);
}

 3.统计二叉树中度为0的节点个数(叶节点)

int NodeCount(BiTree bt){
    if(bt == null) return 0;
    if(bt->lchild == null && bt->rchild == null)
        return 1;
    else
        return NodeCount(bt->lchild) + NodeCount(bt->rchild);
}

 4.计算二叉树高度

int height(BiTree bt){
    if(bt == null) return 0;
    int LHeight = height(bt->left);
    int RHeight = height(bt->right);
    return (LHeight > RHeight ? LHeight : RHeight) + 1;
}

5.计算二叉树最大高度(基于先序遍历)

int count[MaxSize];
int max = -1;
void width(BiTree bt, int k){
    if(bt == null) return;
    count[k]++;    //该层节点数+1
    if(max<count[k]) max = count[k];
    width(bt->lchikd, k+1);
    width(bt->rchild, k+1);
}

6.删除二叉树中所有叶节点

void Del_0(BiTree bt){
    BiTree *p = bt;
    if((p->lchild == null && p->rchild == null) || p == null)
        free(p);
        return;
    if(p->lchild->lchild == null && p->lchild->rchild == null)
        free(p->lchild);    //说明是叶节点，删掉
        p->lchild = null;
    else(p->rchild->lchild == null && p->rchild->rchild == null)
        free(p->rchild);
        p-rchild = null;
    Del_0(p->lchild);
    Del_0(p->rchild);
}

7.计算二叉树指定节点所在层次

int level(BiTree bt, BiTree *p){
    int d1,d2;
    if(bt == null) return 0;
    if(bt == p) return 1;
    d1 = level(bt->lchild, p);
    d2 = level(bt->rchild, p);
    if(d1 || d2) return 1+(d1>d2 ? d1:d2);
    retrun 0;
}

8.交换二叉树左右子树

void swap(BiTree bt){
    if(bt){
        swap(bt->lchild);
        swap(bt->rchild);
        BiTree *temp = bt->lchild;
        bt->lchild = bt->rchild;
        bt->rchild = temp;
    }
}

9.后序遍历非递归算法

void PostOrder(BiTree T){
    InitStack(S);
    BiTree *p = T;
    BiTree *r = null;
    while(p || !IsEmpty(S)){
        if(p){
            Push(S,p);
            p = p->lchild;
        }else{
            GetTop(S,p);
            if(p->rchild && p->rchild != r){    //判断是否有右子树
                p = p->rchild;
            }else{
                Pop(S,p);
                visit(p->data);
                r = p;
                p = null;
            }
        }
    }
}