第十五天|104.二叉树的最大深度、111.二叉树的最小深度、 222.完全二叉树的节点个数

104.二叉树的最大深度

题目链接：104. 二叉树的最大深度 - 力扣（LeetCode）

/**
 * 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:
    int GetDepth(TreeNode* Cur) {
        if (Cur == nullptr) return 0;
        int Left = GetDepth(Cur->left);
        int Right = GetDepth(Cur->right);
        return 1 + max(Left, Right);
    }
    int maxDepth(TreeNode* root) {
        return GetDepth(root);
    }
};

111.二叉树的最小深度

题目链接：111. 二叉树的最小深度 - 力扣（LeetCode）

/**
 * 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:
    int GetMin(TreeNode* Cur) {
        if (Cur == nullptr) return 0;
        int left = GetMin(Cur->left);
        int right = GetMin(Cur->right);
        if (Cur->left != nullptr && Cur->right == nullptr) 
            return 1 + left;
        if (Cur->left == nullptr && Cur->right != nullptr) 
            return 1 + right;
        return 1 + min(left, right);
    }
    int minDepth(TreeNode* root) {
        return GetMin(root);
    }
};

222.完全二叉树的节点个数

题目链接：222. 完全二叉树的节点个数 - 力扣（LeetCode）

/**
 * 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:
    int GetCount(TreeNode* Cur) {
        if (Cur == nullptr) return 0;
        int left = GetCount(Cur->left);
        int right = GetCount(Cur->right);
        return 1 + left + right;
    }
    int countNodes(TreeNode* root) {
        return GetCount(root);
    }
};