Java for LeetCode 111 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.

解题思路：注意minimum depth最后遍历的那个点，left right都必须为null，JAVA实现如下：

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