【leetcode刷题笔记】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.

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题解：递归解决，用私有变量minDep保存最小的深度，每当遍历到叶节点的时候就看是否需要更新。

代码如下：

 /**
  * Definition for binary tree
  * public class TreeNode {
  *     int val;
  *     TreeNode left;
  *     TreeNode right;
  *     TreeNode(int x) { val = x; }
  * }
  */
 public class Solution {
     private int minDep = Integer.MAX_VALUE;
     public void minDepthRecur(TreeNode root,int depth){
         if(root == null)
             return;
         if(root.left == null && root.right == null){
             if(minDep > depth)
                 minDep = depth;
             return;
         }
         minDepthRecur(root.left, depth+1);
         minDepthRecur(root.right, depth+1);
     }
     public int minDepth(TreeNode root) {
         if(root == null)
             return 0;
         minDepthRecur(root, 1);
         return minDep;
     }
 }