111. Minimum Depth of Binary Tree 解题记录

题目描述：

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.

本题要我们写一个找二叉树最小深度分叉的函数，返回最小深度。

解题思路：

本题的解题思路可以参考找二叉树最大深度那题的函数。用递归比较当前节点下两个分支的深度，返回较小深度。

代码：

 

/**
 * 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)
            return 0;
        else if(!root->left)
            return minDepth(root->right)+1;
        else if(!root->right)
            return minDepth(root->left)+1;
        else
            return min(minDepth(root->left),minDepth(root->right))+1;
    }
};