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 minDepth(TreeNode *root) 
    {
        if(!root)
            return 0;
        if(!root->left&&!root->right)
            return 1;
        if(!root->left)
            return 1+minDepth(root->right);
        if(!root->right)
            return 1+minDepth(root->left);
        return 1 + min(minDepth(root->left), minDepth(root->right));
    }
};

考虑全面方正解