Maximum depth of binary tree

Given a binary tree, find its minimum depth.

The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

注意：叶子的返回条件是 root->left == NULL and root ->right == NULL

 1 class Solution {
 2 public:
 3     int minDepth(TreeNode* root) {
 4         if (root == NULL)
 5             return 0;
 6         if (root ->left == NULL && root ->right == NULL)
 7             return 1;
 8         if (root ->left != NULL && root ->right == NULL)
 9             return dfs(root->left,2);
10         if (root ->left == NULL && root ->right != NULL)
11             return dfs(root->right,2);
12         return min(dfs(root->left,2),dfs(root->right,2));
13     }
14     int dfs(TreeNode* root, int depth)
15     {
16         if (root->left == NULL && root->right == NULL)
17             return depth; 
18         if (root ->left != NULL && root ->right == NULL)
19             return dfs(root->left,depth+1);
20         if (root ->left == NULL && root ->right != NULL)
21             return dfs(root->right,depth+1);
22         return min(dfs(root->left,depth+1),dfs(root->right,depth+1));
23     }
24 };

Maximum

 1 class Solution {
 2 public:
 3     int maxDepth(TreeNode* root) {
 4         if (root == NULL)
 5             return 0;
 6         if (root->left || root->right)
 7             return maxDepth(root->left) + maxDepth(root->right) +1 ;
 8         return max(maxDepth(root->left),maxDepth(root->right)) +1; 
 9         
10     }
11 };

posted on 2015-06-08 04:41 又岸阅读(157) 评论(0) 收藏举报