algorithm/Algorithm/cpp/0104.MaximumDepthofBinaryTree/maxDepth.cpp at master · wuvei/algorithm · GitHub

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/**
 * 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 maxDepth(TreeNode* root) {
        int ans=0;
        if(!root) return ans;
        queue<TreeNode *> q;
        q.push(root);
        while (!q.empty()) {
            ans++;
            int len = q.size();
            while (len--) {
                TreeNode *temp = q.front();
                q.pop();
                if (temp -> left) q.push(temp -> left);
                if (temp -> right) q.push(temp -> right);
            }
        }
        return ans;
    }
};


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