题解 | #二叉树的最小深度#

using System;
using System.Collections.Generic;

/*
public class TreeNode
{
    public int val;
    public TreeNode left;
    public TreeNode right;

    public TreeNode (int x)
    {
        val = x;
    }
}
*/

class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param root TreeNode类
     * @return int整型
     */
    public int run (TreeNode root) {
        // write code here
        return BFS(root);
    }

    public int BFS (TreeNode root) {
        // write code here
        if (root == null)
            return 0;
        if (root.left == null)
            return 1 + BFS(root.right);
        if (root.right == null)
            return 1 + BFS(root.left);
        int nLeft = 1 + BFS(root.left);
        int nRight = 1 + BFS(root.right);
        return Math.Min(nLeft, nRight);
    }
}