[leetcode]Minimum 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.

/**
* Definition for binary tree
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
int dfs(TreeNode *root){
if(!root-> left && !root->right) return 1;
if(root -> left && !root -> right) return dfs(root -> left) + 1;
if(!root -> left && root -> right) return dfs(root -> right) + 1;

return min(dfs(root->left), dfs(root->right)) + 1;
}

int minDepth(TreeNode *root) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
if(!root) return 0;

return dfs(root);
}
};