【c语言】构建二叉树并前序遍历

#include <stdio.h>

#include <stdlib.h>

#define SIZE        50

//数的结点结构

typedef struct NODE{

    int data;

    struct NODE *left,*right;

}Node;

typedef struct stack{

    int top;

    Node *db[SIZE];//保存树的结点

}stack;

Node *creat_tree(void)

{

    Node *t;

    int x;

    scanf("%d",&x);

   

    if(x == 0)

        t = NULL;

    else{

        t = (Node*)malloc(sizeof(Node));

        t ->data  = x;

        printf("输入%d结点的左子结点:",t->data);

        t->left = creat_tree();

        printf("输入%d结点的右子结点:",t->data);

        t->right = creat_tree();

    }

    return t;

}

//非递归实现前序遍历二叉树

void preVisit(Node *T)

{

//初始化栈

    stack *s = (stack*)malloc(sizeof(stack));

    s->top = 0;

   

    while(T || s->top > 0){

    if(T){

        printf("3%d",T->data);

        s->db[s->top++] = T;

        T = T->left;

        }

    else{

        T = s->db[--s->top];

        T = T->right;

        }

    }

   

}

//递归实现前序遍历

/*

void preVisit(Node *T)

{

    if(T){

        printf("%d",T->data);

        preVisit(T->left);

        preVisit(T->right);

   

    }

}

*/

int main(void)

{

    Node *T = NULL;

    printf("二叉数的建立，以输入‘0’结束\n");

    printf("输入根结点: ");

    T = creat_tree();

    printf("二叉树建立完毕\n");

    printf("前序遍历二叉树: \n");

    preVisit(T);

    return 0;

}