题解 | 二叉树的最小深度

# class TreeNode:

#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

#
# 
# @param root TreeNode类 
# @return int整型
#层序遍历
class Solution:
    def run(self , root ):
        # write code here
        if not root:
            return 0
        count = 0
        cur = [root]
        nxt = []
        while True:
            count += 1
            for node in cur:
                if not node.right and not node.left:
                    return count
                if node.left:
                    nxt.append(node.left)
                if node.right:
                    nxt.append(node.right)
            cur = nxt
            nxt = []