Leetcode 104. Maximum Depth of binary tree (maximum depth of binary trees)

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along, the longest path from the root node to the farthest leaf node.

Analysis: Finding the maximum depth of a binary tree

Solution One: It is easy to think of recursion (depth-first search)

(1) If the root node is empty, return 0; otherwise go to (2)

(2) L = maximum depth of the left subtree; R = Maximum depth of right subtree; return Max (L, R) + 1;

1 /**2 * Definition for a binary tree node.3 * struct TreeNode {4 * int val;5 * TreeNode *left;6 * TreeNode *right;7 * TreeNode (int x): Val (x), left (null), right (null) {}8  * };9  */Ten classSolution { One  Public: A     intMaxDepth (treenode*root) { -         if(Root = =NULL) -             return 0; the         intL = maxDepth (root->Left ); -         intR = maxDepth (root->Right ); -         returnMax (L, R) +1; -     } +};

Solution Two: I think you can also use Breadth First search: Layer I if the node is not empty, then the depth plus 1 ... The maximum depth is the number of layers in this tree.

1 classSolution {2  Public:3     intMaxDepth (treenode*root) {4         if(Root = =NULL)5             return 0;6         intdepth =0;7Queue<treenode*>Node_que;8treenode*temp;9 Node_que.push (root);Ten          while(!Node_que.empty ()) { One             intSize =node_que.size (); A              while(size--){ -temp =Node_que.front (); - Node_que.pop (); the                 if(Temp->left! =NULL) -Node_que.push (temp->Left ); -                 if(Temp->right! =NULL) -Node_que.push (temp->Right ); +             } -depth++; +         } A         returndepth; at          -     } -};

Leetcode 104. Maximum Depth of binary tree (maximum depth of binary trees)