【LeetCode】Maximum Depth of Binary Tree && Minimum Depth of Binary Tree

1、Maximum Depth of Binary Tree
Total Accepted: 10889 Total Submissions: 24617 My Submissions
Given a binary tree, find its maximum depth.
The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
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2、Minimum Depth of Binary Tree
Total Accepted: 8209 Total Submissions: 28728 My Submissions
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.
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        min和max其实不大一样。
        max到叶子节点，最长路程，其实是一直深度搜索的过程。
        min，需要判断当前是否为叶子节点，这个很重要。

MAX Java AC

/** * Definition for binary tree * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    public int maxDeep;    public int maxDepth(TreeNode root) {        if(root == null){            return 0;        }        maxDeep = 0;        dfs(root, 1);        return maxDeep;    }    public void dfs(TreeNode root, int deep){        if(root == null){            return;        }        maxDeep = Math.max(maxDeep, deep);        dfs(root.left, deep+1);        dfs(root.right, deep+1);    }}

MIN Java AC

/** * Definition for binary tree * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    public int minDeep;    public int minDepth(TreeNode root) {        if(root == null){            return 0;        }        minDeep = Integer.MAX_VALUE;        dfs(root, 1);        return minDeep;    }    public void dfs(TreeNode root, int deep){        if(root.left == null && root.right == null){            minDeep = Math.min(minDeep, deep);            return;        }        if(root.left != null){            dfs(root.left, deep+1);        }        if(root.right != null){            dfs(root.right, deep+1);        }    }}