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226.翻转二叉树.cpp
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226.翻转二叉树.cpp
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#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <queue>
#include <deque>
#include <list>
#include <string>
#include <stack>
using namespace std;
/*
* @lc app=leetcode.cn id=226 lang=cpp
*
* [226] 翻转二叉树
*/
struct TreeNode
{
int val;
TreeNode *left;
TreeNode *right;
TreeNode() : val(0), left(nullptr), right(nullptr) {}
TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
};
// @lc code=start
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
TreeNode* invertTree(TreeNode* root) {
if (!root) {
return root;
}
TreeNode* tmp = NULL;
tmp = root->left;
root->left = root->right;
root->right = tmp;
invertTree(root->left);
invertTree(root->right);
return root;
}
//用迭代法做
TreeNode* invertTree_1(TreeNode* root) {
stack<TreeNode*> ts;
if (root) {
ts.push(root);
}
while (!ts.empty()) {
TreeNode* node = ts.top();
ts.pop();
TreeNode* tmp = node->left;
node->left = node->right;
node->right = tmp;
if (node->right) {
ts.push(node->right);
}
if (node->left) {
ts.push(node->left);
}
}
return root;
}
};
// @lc code=end