LeetCode（226）Invert Binary Tree

题目

分析

交换二叉树的左右子树。

递归非递归两种方法实现。

AC代码

class Solution {
public:
    //递归实现
    TreeNode* invertTree(TreeNode* root) {
        if (!root)
            return root;

        TreeNode *tmp = root->left;
        root->left = invertTree(root->right);
        root->right = invertTree(tmp);

        return root;
    }

    //非递归实现
    TreeNode* invertTree2(TreeNode* root) {
        if (root == NULL)
            return root;
        queue<TreeNode*> tree_queue;
        tree_queue.push(root);

        while (!tree_queue.empty()){
            TreeNode * pNode = tree_queue.front();
            tree_queue.pop();

            TreeNode * pLeft = pNode->left;
            pNode->left = pNode->right;
            pNode->right = pLeft;

            if (pNode->left)
                tree_queue.push(pNode->left);
            if (pNode->right)
                tree_queue.push(pNode->right);
        }
        return root;
    }
};