/** * Definition for binary tree * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public int run(TreeNode root) { if(root==null) return 0; int leftminlength=run(root.left); int rightminlength=run(root.right); if(leftminlength==0&&rightminlength>0) return rightminlength+1; else if(rightminlength==0&&leftminlength>0) return leftminlength+1; else return (leftminlength<rightminlength)?leftminlength+1:rightminlength+1; } }
采用递归的思想。要注意的是,如果左子树为空的话,返回的是右子树的最小深度+1
如果右子树为空的话,返回的是左子树的最小深度为1
如果左右子树都存在的话,返回的是左右子树的最小深度最小值+1