Data structure - tree related algorithm implementation

Basic Algorithms for Binary Trees

Including the traversal of the binary tree (first, middle, and last), the level of the binary tree, the depth of the binary tree, and the calculation of the number of leaf nodes of the binary tree. The relevant algorithm ideas can be read in the book, here is only the relevant algorithm implementation.

Code

#include <stdio.h>
#include <stdlib.h>
#define MAXSIZE 30

typedef char ElemType;

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


int IsEmpty_BiTree(BiTree *T) {
    if(*T == NULL)
    return 1;//如果树为空一直进入死循环，直到输入数据为止 
    else
    return 0;
}

void Create_BiTree(BiTree *T){
    char ch;
    ch = getchar();
    //当输入的是"#"时，认为该子树为空
    if(ch == '#')
        *T = NULL;
    //创建树结点
    else{
        *T = (BiTree)malloc(sizeof(struct TNode));
        (*T)->data = ch; //生成树结点
        //生成左子树
        Create_BiTree(&(*T)->lchild);
        //生成右子树
        Create_BiTree(&(*T)->rchild);
    }
}

void TraverseBiTree(BiTree T) { //先序遍历 
    if(T == NULL)//指针为空，说明节点不存在 
    return; 
    else {
        printf("%c ",T->data);
        TraverseBiTree(T->lchild);
        TraverseBiTree(T->rchild);
    }
    
}

void InOrderBiTree(BiTree T) {      //中序遍历 
    if(NULL == T)
    return;
    else {
        InOrderBiTree(T->lchild);
        printf("%c ",T->data);
        InOrderBiTree(T->rchild);   
    }
}

void PostOrderBiTree(BiTree T) {
    if(NULL == T)
    return;
    else {
        InOrderBiTree(T->lchild);
        InOrderBiTree(T->rchild);
        printf("%c ",T->data);
    }
    
} 

int TreeDeep(BiTree T) {
    int deep = 0;
    if(T)
    {
        int leftdeep = TreeDeep(T->lchild);
        int rightdeep = TreeDeep(T->rchild);
        deep = leftdeep+1 > rightdeep+1 ? leftdeep+1 : rightdeep+1; 
    }
    return deep;
}
//树的叶子结点为 
int Leafcount(BiTree T, int &num) {//一般涉及到变化的都会取地址 
    if(T)
    {
        if(T->lchild ==NULL && T->rchild==NULL) 
        {
            num++;
            printf("%c ",T->data);
        }           
        Leafcount(T->lchild,num);
        Leafcount(T->rchild,num);

    }
    return num;
}

//树的层次显示 （利用队列，先进先出的原则可以完美实现） 
void LevelOrder_BiTree(BiTree T){
    //用一个队列保存结点信息,这里的队列采用的是顺序队列中的数组实现
    int front = 0;
    int rear = 0;
    BiTree BiQueue[MAXSIZE];
    BiTree tempNode;
    if(!IsEmpty_BiTree(&T)){
        BiQueue[rear++] = T;
         
        while(front != rear){// 
            //取出队头元素，并使队头指针向后移动一位　
            tempNode = BiQueue[front++];
            //判断左右子树是否为空,若不为空，则加入队列　
            if(!IsEmpty_BiTree(&(tempNode->lchild)))
                BiQueue[rear++] = tempNode->lchild;
             
            if(!IsEmpty_BiTree(&(tempNode->rchild)))
                BiQueue[rear++] = tempNode->rchild;
             
             printf("%c ",tempNode->data);
        }
    }
}

int main(void)
{
    BiTree T;
    BiTree *p = (BiTree*)malloc(sizeof(BiTree));
    int deepth,num=0 ;
    Create_BiTree(&T);//一般涉及到变化的都会取地址 
    printf("先序遍历二叉树:\n");
    TraverseBiTree(T);
    printf("\n");
    printf("中序遍历二叉树:\n");
    InOrderBiTree(T);
    printf("\n");
    printf("后序遍历二叉树:\n");
    PostOrderBiTree(T);
    printf("\n层次遍历结果：");
    LevelOrder_BiTree(T);
    printf("\n");
    deepth=TreeDeep(T);
    printf("树的深度为:%d",deepth);
    printf("\n");
    printf("树的叶子结点为:");
    Leafcount(T,num);
    printf("\n树的叶子结点个数为:%d",num);
    return 0;
}

Run the demo

Binary tree structure diagram

references

• Data Structure - Described in C Language (Second Edition) [Geng Guohua]