LeetCodeDay14二叉树

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LeetCode226.翻转二叉树

TreeNode* invertTree(TreeNode* root) {
        if(!root) return nullptr;
        else{
            TreeNode* tmp = new TreeNode();
            tmp = root->right;
            root->right = root->left;
            root->left = tmp;
            if(root->left)invertTree(root->left);
            if(root->right)invertTree(root->right);
            return root;
        }
    }

LeetCode101.对称二叉树

class Solution {
public:
    bool isSymmetric(TreeNode* root) {
        return check(root->left,root->right);
    }
    bool check(TreeNode* p, TreeNode* q){
        if(!p && !q )return true;
        if(!p || !q || p->val != q->val)return false;
        else
            return check(p->left,q->right)&&check(p->right,q->left);
    }
};

LeetCode104.二叉树的最大深度

class Solution {
public:
    int maxDepth(TreeNode* root) {
        if(root == nullptr)return 0;
        else
            return 1 + max(maxDepth(root->left), maxDepth(root->right));
    }
};

LeetCode111.二叉树的最小深度

class Solution {
public:
    int minDepth(TreeNode* root) {
        if(!root)return 0;
        else if(!root->left && !root->right)
            return 1;
        else if(!root->left && root->right)
            return 1 + minDepth(root->right);
        else if(root->left && !root->right)
            return 1 + minDepth(root->left);
        else
            return 1 + min(minDepth(root->right), minDepth(root->left));
    }
};