leetcode 226 Invert Binary Tree 翻转二叉树

C++代码，方法层序+互换左右孩子

/**
 * 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:
    TreeNode* invertTree(TreeNode* root) {
        //层序遍历然后互换每一层的左右孩子
        if(root==NULL) return root;
        queue<TreeNode*> q;
        q.push(root);
        while(!q.empty()){
            TreeNode* cur=q.front();
            TreeNode* temp;
            q.pop();
            if(cur->left!=NULL) q.push(cur->left);
            if(cur->right!=NULL) q.push(cur->right);
            if(cur->left!=NULL&&cur->right==NULL){
                cur->right=cur->left;cur->left=NULL;
            }else if(cur->left==NULL&&cur->right!=NULL){
                cur->left=cur->right;cur->right=NULL;
            }else if(cur->left!=NULL&&cur->right!=NULL){
                temp=cur->left;
                cur->left=cur->right;
                cur->right=temp;
            }
        }
        return root;
    }
};