(java)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.

思路：也是穷举法的方法，每次都取最小的深度。当root==null时 return 0；

当root.left!=null || root.right!=null时，return 1+min(minDep(root.left),minDep(root.right));

当root.left或者root.right有一个为空时，返回1+minDep(root.left)+minDep(root.right);

代码如下(已通过leetcode)

public class Solution {
   public int minDepth(TreeNode root) {
       if(root==null) return 0;
       else {
        if(root.left!=null && root.right!=null ) return 1+Math.min(minDepth(root.left), minDepth(root.right));
        else return 1+minDepth(root.left)+minDepth(root.right);
       }
      
   }
   
  
}