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hello-algo/codes/c/chapter_tree/binary_tree_dfs.c

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/**
* File: binary_tree_dfs.c
* Created Time: 2023-01-11
* Author: Reanon (793584285@qq.com)
*/
#include "../utils/common.h"
#define MAX_SIZE 100
// 辅助数组,用于存储遍历序列
int *arr;
/* 前序遍历 */
void preOrder(TreeNode *root, int *size) {
if (root == NULL)
return;
// 访问优先级:根节点 -> 左子树 -> 右子树
arr[(*size)++] = root->val;
preOrder(root->left, size);
preOrder(root->right, size);
}
/* 中序遍历 */
void inOrder(TreeNode *root, int *size) {
if (root == NULL)
return;
// 访问优先级:左子树 -> 根节点 -> 右子树
inOrder(root->left, size);
arr[(*size)++] = root->val;
inOrder(root->right, size);
}
/* 后序遍历 */
void postOrder(TreeNode *root, int *size) {
if (root == NULL)
return;
// 访问优先级:左子树 -> 右子树 -> 根节点
postOrder(root->left, size);
postOrder(root->right, size);
arr[(*size)++] = root->val;
}
/* Driver Code */
int main() {
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
int nums[] = {1, 2, 3, 4, 5, 6, 7};
int size = sizeof(nums) / sizeof(int);
TreeNode *root = arrayToTree(nums, size);
printf("初始化二叉树\n");
printTree(root);
/* 前序遍历 */
// 初始化辅助数组
arr = (int *)malloc(sizeof(int) * MAX_SIZE);
size = 0;
preOrder(root, &size);
printf("前序遍历的节点打印序列 = ");
printArray(arr, size);
/* 中序遍历 */
size = 0;
inOrder(root, &size);
printf("中序遍历的节点打印序列 = ");
printArray(arr, size);
/* 后序遍历 */
size = 0;
postOrder(root, &size);
printf("后序遍历的节点打印序列 = ");
printArray(arr, size);
return 0;
}