1.求二叉树的最小深度:
public class Solution { public int run(TreeNode root) { if(root==null) return 0; int l = run(root.left); int r = run(root.right); if(l==0 || r==0) return l+r+1; return Math.min(l,r)+1; } } class TreeNode { int val; TreeNode left; TreeNode right; }