c++写出默克树ABCDE的非递归中序遍历

非递归中序遍历默克树ABCDE的代码如下：

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

#define MAXSIZE 100
#define LEFT 0
#define RIGHT 1

typedef struct TreeNode {
    char data;
    struct TreeNode *left, *right;
    int flag;
} TreeNode;

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

// 初始化栈
void initStack(Stack* s) {
    s->top = -1;
}

// 判断栈是否为空
int isStackEmpty(Stack* s) {
    return s->top == -1;
}

// 判断栈是否已满
int isStackFull(Stack* s) {
    return s->top == MAXSIZE-1;
}

// 入栈
void push(Stack* s, TreeNode* p) {
    if (!isStackFull(s)) {
        s->data[++s->top] = p;
    }
}

// 出栈
TreeNode* pop(Stack* s) {
    if (!isStackEmpty(s)) {
        return s->data[s->top--];
    }
    return NULL;
}

// 非递归中序遍历
void inorderTraverse(TreeNode* root) {
    Stack s;
    TreeNode* p = root;
    initStack(&s);
    while (p || !isStackEmpty(&s)) {
        if (p) {
            push(&s, p);
            p = p->left;
        } else {
            p = pop(&s);
            if (!p->flag) {
                printf("%c ", p->data);
                p->flag = RIGHT;
                push(&s, p);
                p = p->right;
            } else {
                p = NULL;
            }
        }
    }
}

int main() {
    // 构建默克树ABCDE
    TreeNode* A = (TreeNode*)malloc(sizeof(TreeNode));
    A->data = 'A';
    A->left = NULL;
    A->right = NULL;
    A->flag = LEFT;

    TreeNode* B = (TreeNode*)malloc(sizeof(TreeNode));
    B->data = 'B';
    B->left = NULL;
    B->right = NULL;
    B->flag = LEFT;

    TreeNode* C = (TreeNode*)malloc(sizeof(TreeNode));
    C->data = 'C';
    C->left = A;
    C->right = B;
    C->flag = LEFT;

    TreeNode* D = (TreeNode*)malloc(sizeof(TreeNode));
    D->data = 'D';
    D->left = NULL;
    D->right = NULL;
    D->flag = LEFT;

    TreeNode* E = (TreeNode*)malloc(sizeof(TreeNode));
    E->data = 'E';
    E->left = C;
    E->right = D;
    E->flag = LEFT;

    // 中序遍历
    inorderTraverse(E);

    return 0;
}

输出结果为：A C B E D。