数据结构第三次作业第一题（表达式树）

原创于 2020-11-06 19:39:41 发布 · 162 阅读

CC 4.0 BY-SA版权

该博客主要介绍了如何使用栈实现二叉树的前序遍历。通过读取字符数组构建二叉树，并利用push和pop操作进行遍历。代码中定义了树和栈的数据结构，实现了push和pop函数，最后展示了一个简单的前序遍历过程。

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#include <stdio.h>
#include <stdlib.h>

typedef struct tree
{
    struct tree *left;
    struct tree *right;
    char data;
} Tree;

typedef struct stack
{
    int top;
    Tree *data[31];
} Stack;

void push(Stack *S, Tree *root)
{
    if (S->top < 30)
        S->data[++S->top] = root;
    return;
}

Tree *pop(Stack *S)
{
    if (S->top != -1)
        return S->data[S->top--];
    else
        return NULL;
}

void preorder(Tree *root)
{
    if (root)
    {
        printf("%c ", root->data);
        preorder(root->left);
        preorder(root->right);
    }
}

int main()
{

    char a[100];
    gets(a);
    int i = 0;
    Tree *root = NULL;
    Stack *S = (Stack *)malloc(sizeof(Stack));
    S->top = -1;
    while (a[i])
    {
        if (a[i] >= '0' && a[i] <= '9')
        {
            root = (Tree *)malloc(sizeof(Tree));
            root->left = root->right = NULL;
            root->data = a[i];
            push(S, root);
        }
        else if(a[i]!=' ')
        {
            root = (Tree *)malloc(sizeof(Tree));
            root->right = pop(S);
            root->left = pop(S);
            root->data = a[i];
            push(S, root);
        }
        i++;
    }
    root = pop(S);
    preorder(root);
    return 0;
}