二叉树题目----1 前序中序后序遍历二叉树并返回相应的遍历(不是打印)

前序遍历

在这里插入图片描述

/*** Definition for a binary tree node.* struct TreeNode {*     int val;*     struct TreeNode *left;*     struct TreeNode *right;* };*//*** Note: The returned array must be malloced, assume caller calls free().*/
int *array;
int size;void _preorderTraversal(struct TreeNode *root){if(root == NULL){return ;}//处理根结点array[size++]=root->val;_preorderTraversal(root->left);_preorderTraversal(root->right);
}int* preorderTraversal(struct TreeNode* root, int* returnSize){array = (int *)malloc(sizeof(int)*100*1000);size =0  ;_preorderTraversal(root);*returnSize = size;return array;
}

中序遍历

在这里插入图片描述

/*** Definition for a binary tree node.* struct TreeNode {*     int val;*     struct TreeNode *left;*     struct TreeNode *right;* };*//*** Note: The returned array must be malloced, assume caller calls free().*/int *array;
int size;void _preorderTraversal(struct TreeNode *root){if (root == NULL){return;}//处理根结点_preorderTraversal(root->left);array[size++] = root->val;_preorderTraversal(root->right);
}int* inorderTraversal(struct TreeNode* root, int* returnSize){array = (int *)malloc(sizeof(int)* 100 * 1000);size = 0;_preorderTraversal(root);*returnSize = size;return array;
}

后序遍历

在这里插入图片描述

/*** Definition for a binary tree node.* struct TreeNode {*     int val;*     struct TreeNode *left;*     struct TreeNode *right;* };*//*** Note: The returned array must be malloced, assume caller calls free().*/int *array;
int size;void _preorderTraversal(struct TreeNode *root){if (root == NULL){return;}//处理根结点_preorderTraversal(root->left);_preorderTraversal(root->right);array[size++] = root->val;
}
int* postorderTraversal(struct TreeNode* root, int* returnSize){array = (int *)malloc(sizeof(int)* 100 * 1000);size = 0;_preorderTraversal(root);*returnSize = size;return array;
}