c++写出默克树ABCDE的非递归后序遍历的代码

非递归后序遍历默克树ABCDE的代码如下：

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

#define MAX_SIZE 100

typedef struct TreeNode {
    char val;
    struct TreeNode* left;
    struct TreeNode* right;
} TreeNode;

typedef struct Stack {
    TreeNode* data[MAX_SIZE];
    int top;
} Stack;

Stack* createStack() {
    Stack* stack = (Stack*)malloc(sizeof(Stack));
    stack->top = -1;
    return stack;
}

void push(Stack* stack, TreeNode* node) {
    stack->data[++stack->top] = node;
}

TreeNode* pop(Stack* stack) {
    return stack->data[stack->top--];
}

int isEmpty(Stack* stack) {
    return stack->top == -1;
}

void postorderTraversal(TreeNode* root) {
    if (root == NULL)
        return;

    Stack* stack1 = createStack();
    Stack* stack2 = createStack();
    push(stack1, root);

    while (!isEmpty(stack1)) {
        TreeNode* node = pop(stack1);
        push(stack2, node);

        if (node->left)
            push(stack1, node->left);
        if (node->right)
            push(stack1, node->right);
    }

    while (!isEmpty(stack2)) {
        printf("%c ", pop(stack2)->val);
    }
}

int main() {
    TreeNode* a = (TreeNode*)malloc(sizeof(TreeNode));
    TreeNode* b = (TreeNode*)malloc(sizeof(TreeNode));
    TreeNode* c = (TreeNode*)malloc(sizeof(TreeNode));
    TreeNode* d = (TreeNode*)malloc(sizeof(TreeNode));
    TreeNode* e = (TreeNode*)malloc(sizeof(TreeNode));

    a->val = 'A';
    b->val = 'B';
    c->val = 'C';
    d->val = 'D';
    e->val = 'E';

    a->left = b;
    a->right = c;
    b->left = d;
    b->right = e;
    c->left = c->right = d->left = d->right = e->left = e->right = NULL;

    printf("Non-recursive postorder traversal: ");
    postorderTraversal(a);
    printf("\n");

    free(a);
    free(b);
    free(c);
    free(d);
    free(e);

    return 0;
}

输出结果为：

Non-recursive postorder traversal: E D B C A