1.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.

2.解法分析

/**

* 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) {

// Start typing your C/C++ solution below

// DO NOT write int main() function

if(root == NULL)return 0;

if(!root->left&&!root->right)return 1;

if(root->left&&root->right)

{

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

}

else

{

if(root->left)return minDepth(root->left)+1;

else return minDepth(root->right)+1;

}

}

};