题目描述:

##求给定二叉树的最小深度。最小深度是指树的根结点到最近叶子结点的最短路径上结点的数量。
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.

解:

public int run(TreeNode root) {
         if(root==null){
             return 0;
         }
        int left  = run(root.left);
        int right  = run(root.right);
        if(left*right >0){
            return (left>right?right:left)+1;
        }else{
            return (left>right?left:right)+1;
        }
    }