begeekmyfriend / leetcode Goto Github PK

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

struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
};

struct Stack {
    struct TreeNode* node;
    struct Stack* next;
};

void push(struct Stack** stack, struct TreeNode* node) {
    struct Stack* new_node = (struct Stack*)malloc(sizeof(struct Stack));
    if (new_node == NULL) {
        exit(1);
    }
    new_node->node = node;
    new_node->next = *stack;
    *stack = new_node;
}

struct TreeNode* pop(struct Stack** stack) {
    if (*stack == NULL) {
        return NULL;
    }
    struct Stack* top = *stack;
    struct TreeNode* node = top->node;
    *stack = top->next;
    free(top);
    return node;
}

int isEmpty(struct Stack* stack) {
    return stack == NULL;
}

void inorderTraversal(struct TreeNode* root) {
    struct Stack* stack = NULL;
    struct TreeNode* current = root;

    while (current != NULL || !isEmpty(stack)) {
        while (current != NULL) {
            push(&stack, current);
            current = current->left;
        }
        current = pop(&stack);
        printf("%d ", current->val);
        current = current->right;
    }
}