【python-leetcode111-树的宽度遍历】二叉树的最小深度

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def minDepth(self, root: TreeNode) -> int:
        if  not root:
            return 0
        queue=[root]
        res=[]
        depth=0
        while queue:
            depth=depth+1
            l=len(queue)
            for i in range(l):
                t=queue.pop(0)
                if not t.left and not t.right:
                    return depth
                if t.left:
                    queue.append(t.left)
                if t.right:
                    queue.append(t.right)