LeetCode 114.Flatten Binary Tree to Linked List (二叉树展开为链表)
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2022-05-21 19:18:18
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题目描述:
给定一个二叉树,原地将它展开为链表。
例如,给定二叉树
1 / \ 2 5 / \ \ 3 4 6
将其展开为:
1 \ 2 \ 3 \ 4 \ 5 \ 6
AC C++ Solution:
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
void flatten(TreeNode* root) {
TreeNode* now = root;
while(now) {
if(now->left)
{
TreeNode *pre = now->left;
while(pre->right) {
pre = pre->right;
}
pre->right = now->right; //将当前节点的右子树转接到左子节点的右叶节点上
now->right = now->left; //将当前节点的右子树用左子树代替
now->left = NULL;
}
now = now->right; //遍历下一个节点
}
}
};
类似的:
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
void flatten(TreeNode* root) {
while(root) {
if(root->left && root->right) {
TreeNode* t = root->left;
while(t->right)
t = t->right;
t->right = root->right; //将当前节点的右子树接到左子树的右叶节点上
}
if(root->left)
root->right = root->left; //再将当前节点的右子树替换为左子树
root->left = NULL;
root = root->right;
}
}
};
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