Leetcode: Minimum Depth of Binary Tree 理解分析

/**
* Definition for binary tree
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }
*/
public class Solution {
private int min = Integer.MAX_VALUE;
private int count = 0;
public int minDepth(TreeNode root) {
if(root == null)    return 0;
count ++;
if(count > min) return min;
if(root.left == null && root.right == null) {
return count;
}
if(root.left != null) {
int res = minDepth(root.left);
if(res < min)   min = res;
count --;
}
if(root.right != null) {
int re = minDepth(root.right);
if(re < min)    min = re;
count --;
}
return min;
}
}