minimum depth of binary tree
题目描述 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.
/**
* 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;
if(root.left ==null && root.right == null)
return 1;
if(root.left==null)
return run(root.right) + 1;
if(root.right==null)
return run(root.left) + 1;
return Math.min(run(root.left),run(root.right))+1;
}
}