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目录
结点的度:一个结点含有子结点的个数,称为结点的度。如A点的度为6.
叶子节点/终端结点:度为零的结点,也就是没有子结点的结点,如B\C\H\I等结点。
分支结点/非终端节点:度不为零的结点,如D,E,F,G,J。
双亲节点或父节点:若一个节点有子节点,则称这个节点为其子节点的父节点或者双亲节点。
兄弟节点:有相同父节点的节点称为兄弟节点,如图B,C是兄弟节点。
树的度:一棵树中最大的结点的度称为树的度。如图,该树的度为6.
树的高度/层次:树中节点的层次,如图:树的高度为4.
节点的祖先:从根到该节点上的所有节点,如A是所有节点的祖先。
森林:多颗不相交的树叫森林,并查集就是一个森林。
左孩子右兄弟表示方法:
双亲表示法:
树的主要运用于文件目录
二叉树是度不超过2的树,有左右之分,不可颠倒,如下图:
完全二叉树和非完全二叉树:
完全二叉树是所有节点按照从左到右依次标号而成的,如图:
顺序存储结构只适用于完全二叉树,因此,想将顺序存储普通二叉树,必须先将其转化为完全二叉树。
例如下图:
其顺序存储如下图:
由于顺序存储方式要将普通二叉树转换成完全二叉树,会浪费很多空间,所以链式存储会更适合于二叉树的存储。
链式节点构成:
Lchild:指向左孩子的指针;
Rchild:指向右孩子的指针;
data:节点的数据域;
节点定义:
- typedef struct BinTreeNode
- {
- TreeValType data;//数据域
- struct BinTreeNode *lchild, *rchlid;//左右孩子
- struct BinTreeNode *parent;
- }BTNode,*BiTree;
创建二叉树:
- void CreateBinTree(BinTree *t)
- {
- *t = (BinTree*)malloc(sizeof(BinTree));
- (*t)->data = 1;
- (*t)->lchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->data = 2;
- (*t)->rchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->rchild->data = 3;
- (*t)->rchild->lchild = NULL;
- (*t)->rchild->rchild = NULL;
- (*t)->lchild->lchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->rchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->lchild->data = 4;
- (*t)->lchild->rchild->data = 5;
- (*t)->lchild->lchild->lchild = NULL;
- (*t)->lchild->lchild->rchild = NULL;
- (*t)->lchild->rchild->rchild = NULL;
- (*t)->lchild->rchild->lchild = NULL;
- }
- #include<stdio.h>
- #include<stdlib.h>
- #define TreeValType int
-
- typedef struct BinTreeNode
- {
- TreeValType data;//数据域
- struct BinTreeNode *lchild, *rchild;//左右孩子
- struct BinTreeNode *parent;
- }BTNode,*BinTree;
-
- void CreateBinTree(BinTree *t)
- {
- *t = (BinTree*)malloc(sizeof(BinTree));
- (*t)->data = 1;
- (*t)->lchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->data = 2;
- (*t)->rchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->rchild->data = 3;
- (*t)->rchild->lchild = NULL;
- (*t)->rchild->rchild = NULL;
- (*t)->lchild->lchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->rchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->lchild->data = 4;
- (*t)->lchild->rchild->data = 5;
- (*t)->lchild->lchild->lchild = NULL;
- (*t)->lchild->lchild->rchild = NULL;
- (*t)->lchild->rchild->rchild = NULL;
- (*t)->lchild->rchild->lchild = NULL;
- }
-
- int main()
- {
- BinTree Tree;
- CreateBinTree(&Tree);
- printf("%d\n", Tree->lchild->rchild->data);
- getchar();
- return 0;
- }
运行结果:
二叉树的基本遍历方法如下:
先遍历根,再遍历左子树,在遍历右子树:
先序遍历采用的是递归的思想:
- #include<stdio.h>
- #include<stdlib.h>
- #define TreeValType int
-
- typedef struct BinTreeNode
- {
- TreeValType data;//数据域
- struct BinTreeNode *lchild, *rchild;//左右孩子
- struct BinTreeNode *parent;
- }BTNode,*BinTree;
-
- void CreateBinTree(BinTree *t)//创建二叉树
- {
- *t = (BinTree*)malloc(sizeof(BinTree));
- (*t)->data = 1;
- (*t)->lchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->data = 2;
- (*t)->rchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->rchild->data = 3;
- (*t)->rchild->lchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->rchild->rchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->lchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->rchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->lchild->data = 4;
- (*t)->lchild->rchild->data = 5;
- (*t)->rchild->rchild->data = 7;
- (*t)->rchild->lchild->data = 6;
- (*t)->lchild->lchild->lchild = NULL;
- (*t)->lchild->lchild->rchild = NULL;
- (*t)->lchild->rchild->rchild = NULL;
- (*t)->lchild->rchild->lchild = NULL;
- (*t)->rchild->lchild->lchild = NULL;
- (*t)->rchild->lchild->rchild = NULL;
- (*t)->rchild->rchild->rchild = NULL;
- (*t)->rchild->rchild->lchild = NULL;
- }
-
- void displayVal(BTNode * Val)
- {
-
- printf("%d", Val->data);
- }
-
- //先序遍历二叉树
- void PreOrderTraverse(BinTree t)
- {
- if (t != NULL)
- {
- displayVal(t);
- PreOrderTraverse(t->lchild);//访问左孩子
- PreOrderTraverse(t->rchild);//访问右孩子
- }
- return;
- }
-
- int main()
- {
- BinTree Tree;
- CreateBinTree(&Tree);
- printf("先序遍历:\n");
- PreOrderTraverse(Tree);
- getchar();
- return 0;
- }
运行结果:
递归的底层是栈的存取结构思想,故二叉树的先序遍历既可以直接采用递归思想实现,也可以使用栈的存储结构模拟递归的思想实现
非递归实现:
非递归的基本思路:使用堆栈
遇到一个结点,就访问它,并去遍历它的右子树;
如果有右孩子,压栈;
然后先序再去遍历它的左孩子。
- #include<stdio.h>
- #include<stdlib.h>
- #include<string.h>
-
- #define TreeValType int
- int top = -1;//初始栈顶元素所在位置
-
- //构造节点结构体
- typedef struct BinTreeNode
- {
- TreeValType data;
- struct BinTreeNode * lchild, *rchild;
- }BTNode,*BTree;
-
- //初始化树的函数
- void CreateBinTree(BTree *t)
- {
- *t = (BTree*)malloc(sizeof(BTree));
- (*t)->data = 1;
- (*t)->lchild = (BTree*)malloc(sizeof(BTree));
- (*t)->rchild = (BTree*)malloc(sizeof(BTree));
- (*t)->lchild->data = 2;
- (*t)->rchild->data = 3;
- (*t)->lchild->lchild = (BTree*)malloc(sizeof(BTree));
- (*t)->lchild->rchild = (BTree*)malloc(sizeof(BTree));
- (*t)->lchild->lchild->data = 4;
- (*t)->lchild->rchild->data = 5;
- (*t)->rchild->lchild = (BTree*)malloc(sizeof(BTree));
- (*t)->rchild->rchild = (BTree*)malloc(sizeof(BTree));
- (*t)->rchild->lchild->data = 6;
- (*t)->rchild->rchild->data = 7;
- (*t)->lchild->lchild->lchild = NULL;
- (*t)->lchild->lchild->rchild = NULL;
- (*t)->lchild->rchild->lchild = NULL;
- (*t)->lchild->rchild->rchild = NULL;
- (*t)->rchild->lchild->lchild = NULL;
- (*t)->rchild->lchild->rchild = NULL;
- (*t)->rchild->rchild->lchild = NULL;
- (*t)->rchild->rchild->rchild = NULL;
- }
- //前序遍历使用的进栈函数
- void push(BTree** a, BTNode* Val)
- {
- a[++top] = Val;
- }
-
- //出栈函数
- void pop()
- {
- if (top ==-1)
- {
- return;
- }
- top--;
- }
-
- void displayVal(BTNode* Val)
- {
- printf("%d",Val->data);
- }
-
- //获取栈顶元素
- BTNode* gettop(BTNode**a)
- {
- return a[top];
- }
- //先序遍历非递归算法
- void preOrderTraverse(BTree tree)
- {
- BTNode* a[20];//定义顺序栈
- BTNode* p;//定义临时指针
- push(a, tree);
- while (top != -1)
- {
- p = gettop(a);//取栈顶元素
- pop();//弹栈
- while (p)
- {
- displayVal(p);
- //如果结点有右孩子,右孩子进栈
- if (p->rchild)
- {
- push(a, p->rchild);
- }
- p = p->lchild;//一直指向根节点的最后一个左孩子
- }
- }
- }
- int main()
- {
- BTree tree;
- CreateBinTree(&tree);
- printf("先序遍历:\n");
- preOrderTraverse(tree);
- getchar();
- return 0;
- }
运行结果:
与前面运行结果一致。
中序遍历:左子树,根节点,右子树
递归实现:
- #include<stdio.h>
- #include<stdlib.h>
- #define TreeValType int
-
- typedef struct BinTreeNode
- {
- TreeValType data;
- struct BinTreeNode * lchild, *rchild;
- }BTNode,*BinTree;
-
- void CreateBinTree(BinTree *t)
- {
- *t = (BinTree*)malloc(sizeof(BinTree));
- (*t)->data = 1;
- (*t)->rchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->data = 2;
- (*t)->rchild->data = 3;
- (*t)->rchild->lchild= (BinTree*)malloc(sizeof(BinTree));
- (*t)->rchild->rchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->lchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->rchild = (BinTree*)malloc(sizeof(BinTree));
- (*t)->lchild->lchild->data = 4;
- (*t)->lchild->rchild->data = 5;
- (*t)->rchild->lchild ->data = 6;
- (*t)->rchild->rchild->data = 7;
- (*t)->lchild->lchild->lchild = NULL;
- (*t)->lchild->lchild->rchild = NULL;
- (*t)->lchild->rchild->lchild = NULL;
- (*t)->lchild->rchild->rchild = NULL;
- (*t)->rchild->lchild->lchild = NULL;
- (*t)->rchild->lchild->rchild = NULL;
- (*t)->rchild->rchild->lchild = NULL;
- (*t)->rchild->rchild->rchild = NULL;
- }
-
- //输出节点本身的值
- void displayVal(BTNode * Val)
- {
- printf("%d", Val->data);
- }
-
- //中序遍历
- void MidOrderTraverse(BinTree t)
- {
- if (t != 0)
- {
- MidOrderTraverse(t->lchild);//遍历左孩子
- displayVal(t);
- MidOrderTraverse(t->rchild);
- }
- //节点为空,返回上一层
- return;
- }
-
- int main()
- {
- BinTree tree;
- CreateBinTree(&tree);
- printf("中序遍历:\n");
- MidOrderTraverse(tree);
- getchar();
- }
运行结果:
后序遍历:左右根;
- #include <stdio.h>
- #include <string.h>
- #include<stdlib.h>
- #define TreevaleType int
- //构造结点的结构体
- typedef struct BiTNode{
- TreevaleType data;//数据域
- struct BiTNode *lchild, *rchild;//左右孩子指针
- }BiTNode, *BiTree;
- //初始化树的函数
- void CreateBiTree(BiTree *T){
- *T = (BiTNode*)malloc(sizeof(BiTNode));
- (*T)->data = 1;
- (*T)->lchild = (BiTNode*)malloc(sizeof(BiTNode));
- (*T)->rchild = (BiTNode*)malloc(sizeof(BiTNode));
-
- (*T)->lchild->data = 2;
- (*T)->lchild->lchild = (BiTNode*)malloc(sizeof(BiTNode));
- (*T)->lchild->rchild = (BiTNode*)malloc(sizeof(BiTNode));
- (*T)->lchild->rchild->data = 5;
- (*T)->lchild->rchild->lchild = NULL;
- (*T)->lchild->rchild->rchild = NULL;
- (*T)->rchild->data = 3;
- (*T)->rchild->lchild = (BiTNode*)malloc(sizeof(BiTNode));
- (*T)->rchild->lchild->data = 6;
- (*T)->rchild->lchild->lchild = NULL;
- (*T)->rchild->lchild->rchild = NULL;
- (*T)->rchild->rchild = (BiTNode*)malloc(sizeof(BiTNode));
- (*T)->rchild->rchild->data = 7;
- (*T)->rchild->rchild->lchild = NULL;
- (*T)->rchild->rchild->rchild = NULL;
- (*T)->lchild->lchild->data = 4;
- (*T)->lchild->lchild->lchild = NULL;
- (*T)->lchild->lchild->rchild = NULL;
- }
-
- //模拟操作结点元素的函数,输出结点本身的数值
- void displayVale(BiTNode* vale){
- printf("%d ", vale->data);
- }
- //后序遍历
- void LastOrderTraverse(BiTree T){
- if (T) {
- LastOrderTraverse(T->lchild);//遍历左孩子
- LastOrderTraverse(T->rchild);//遍历右孩子
- displayVale(T);//调用操作结点数据的函数方法
- }
- //如果结点为空,返回上一层
- return;
- }
- int main() {
- BiTree Tree;
- CreateBiTree(&Tree);
- printf("后序遍历: \n");
- LastOrderTraverse(Tree);
- getchar();
- }
运行结果:
与手工迭代一致。
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