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.

 

注意与求树的高度的区别。

 

C++实现代码：

#include<iostream>

#include<new>

#include<vector>

using namespace std;



//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)

        {

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

                return 1;

            int lmin=minDepth(root->left);

            int rmin=minDepth(root->right);

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

                return lmin+1;

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

                return rmin+1;

            return (lmin<= rmin)?(lmin+1):(rmin+1);

        }

        return 0;

    }

    void createTree(TreeNode *&root)

    {

        int i;

        cin>>i;

        if(i!=0)

        {

            root=new TreeNode(i);

            if(root==NULL)

                return;

            createTree(root->left);

            createTree(root->right);

        }

    }

};

int main()

{

    Solution s;

    TreeNode *root;

    s.createTree(root);

    cout<<s.minDepth(root)<<endl;

}