/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
int minDepth(TreeNode* root) {
if(root == nullptr)
return 0;
if(root->left == nullptr)
return minDepth(root->right) + 1;
if(root->right == nullptr)
return minDepth(root->left) + 1;
return min(minDepth(root->left), minDepth(root->right)) + 1;
}
};